For this tutorial you will need PSP 7 and my selections, presets and wood pattern and a basic knowledge of PSP.
Download my zipfile with selections and wood pattern here.

Put the selections in your selectionsfolder, if you don't have one, make one now. Unzip the presets to your presets folder. Colorize the wood pattern to a color of your liking.

Remember SAVE often !

Ok let's get started.

Open a new transparant image 500 x 500 pixels, set your foreground to the woodpattern of your choice to scale 40, angle 90. Your background pattern use the same woodpattern only set it to scale 40, angle 0.

Add a new raster layer (2), go to selections and select 1-legs-01, floodfill your selection with your foreground pattern. Invert selection and apply a drop shadow with a darker color of your woodpattern. The settings are, offset H & V = 0, opacity = 60, blur = 35.
Deselect. Add noise uniform = 6%.

Add a new raster layer (3), go to selections and select 2-legs-01, floodfill your selection with your background pattern. Invert selection and apply a drop shadow with a darker color of your woodpattern. The settings are, offset H & V = 0, opacity = 40, blur = 10.
Deselect. Add noise uniform = 6%.

Add a new raster layer (4), go to selections and select 3-legs-02, floodfill your selection with your background pattern. Invert selection and apply a drop shadow with a darker color of your woodpattern. The settings are, offset H & V = 0, opacity = 60, blur = 35.
Deselect. Add noise uniform = 6%.

Add a new raster layer (5), go to selections and select 4-2-legs-02, floodfill your selection with your background pattern. Invert selection and apply a drop shadow with a darker color of your woodpattern. The settings are, offset H & V = 0, opacity = 60, blur = 35.
Deselect. Add noise uniform = 6%.

Add a new raster layer (6), go to selections and select 4-legs-02, floodfill your selection with your background pattern. Invert selection and apply a drop shadow with a darker color of your woodpattern. The settings are, offset H & V = 0, opacity = 40, blur = 10.
Deselect. Add noise uniform = 6%.

Add a new raster layer (7), go to selections and select 5-cab-1, floodfill your selection with your foreground pattern. Invert selection and apply a drop shadow with a darker color of your woodpattern. The settings are, offset H & V = 0, opacity = 50, blur = 25.
Deselect. Add noise uniform = 6%.

Add a new raster layer (8), go to selections and select 6-cab-2, floodfill your selection with your background pattern. Invert selection and apply a drop shadow with a darker color of your woodpattern. The settings are, offset H & V = 0, opacity = 60, blur = 35.
Deselect. Add noise uniform = 6%.

Add a new raster layer (9), go to selections and select 7-desk, floodfill your selection with your foreground pattern. Invert selection and apply a drop shadow with a darker color of your woodpattern. The settings are, offset H & V = 0, opacity = 60, blur = 35.
Deselect. Add noise uniform = 6%.

Add a new raster layer (10), go to selections and select 8-draw, floodfill your selection with your foreground pattern. Invert selection and apply a drop shadow with a darker color of your woodpattern. The settings are, offset H & V = 1, opacity = 60, blur = 35.
Deselect. Apply inner bevel AS-drawers. Add noise uniform = 6%.

Add a new raster layer (11), go to selections and select 9-desk-flat, floodfill your selection with your foreground pattern. Invert selection and apply a drop shadow with a darker color of your woodpattern. The settings are, offset H & V = 0, opacity = 60, blur = 35. Deselect. Add noise uniform = 6%.

Add a new raster layer (12), go to selections and select 10-topdeskflat, floodfill your selection with your foreground pattern. Invert selection and apply a drop shadow with a darker color of your woodpattern. The settings are, offset H & V = 0, opacity = 40, blur = 10. Deselect. Add noise uniform = 6%.

Add a new raster layer (13), go to selections and select 11-topdesk-r-side, floodfill your selection with your background pattern. Invert selection and apply a drop shadow with a darker color of your woodpattern. The settings are, offset H & V = 0, opacity = 60, blur = 35. Deselect. Go to colors, adjust brightness/contrast apply brightness = -10, contrast = 0. Add noise uniform = 6%.

Add a new raster layer (14), go to selections and select 12-topdesk-l-side, floodfill your selection with your background pattern. Invert selection and apply a drop shadow with a darker color of your woodpattern. The settings are, offset H & V = 0, opacity = 60, blur = 35. Deselect. Go to colors, adjust brightness/contrast apply brightness = -10, contrast = 0. Add noise uniform = 6%.

Remember to save your work and take a break.

Add a new raster layer (15), go to selections and select 13-topdeskshelf, floodfill your selection with your foreground pattern. Invert selection and apply a drop shadow with a darker color of your woodpattern. The settings are, offset H & V = 0, opacity = 40, blur = 10. Deselect. Go to colors, adjust brightness/contrast apply brightness = -20, contrast = 0. Add noise uniform = 6%.

Add a new raster layer (16), go to selections and select 14-topdraw-1, floodfill your selection with your background pattern. Invert selection and apply a drop shadow with a darker color of your woodpattern. The settings are, offset H & V = 0, opacity = 40, blur = 10. Deselect. Add noise uniform = 6%.

Add a new raster layer (17), go to selections and select 15-topdraw-2, floodfill your selection with your foreground pattern. Invert selection and apply a drop shadow with a darker color of your woodpattern. The settings are, offset H & V = 0, opacity = 60, blur = 35. Deselect. Go to colors, adjust brightness/contrast apply brightness = -10, contrast = 0. Add noise uniform = 6%.

Add a new raster layer (18), go to selections and select 16-topdraw-3, floodfill your selection with your background pattern. Invert selection and apply a drop shadow with a darker color of your woodpattern. The settings are, offset H & V = 0, opacity = 40, blur = 10. Deselect. Apply my inner bevel preset AS-drawers. Add noise uniform = 6%.

Add a new raster layer (19), go to selections and select 17-strip-1, floodfill your selection with your foreground pattern. Invert selection and apply a drop shadow with a darker color of your woodpattern. The settings are, offset H & V = 0, opacity = 40, blur = 10. Deselect. Go to colors, adjust brightness/contrast apply brightness = -20, contrast = 0. Add noise uniform = 6%.

Add a new raster layer (20), go to selections and select 18-strip-2, floodfill your selection with your foreground pattern. Invert selection and apply a drop shadow with a darker color of your woodpattern. The settings are, offset H & V = 0, opacity = 40, blur = 10. Deselect. Go to colors, adjust brightness/contrast apply brightness = -10, contrast = 0. Add noise uniform = 6%.

Add a new raster layer (21), go to selections and select 19-strip-3, floodfill your selection with your foreground pattern. Invert selection and apply a drop shadow with a darker color of your woodpattern. The settings are, offset H & V = 0, opacity = 40, blur = 10. Deselect. Go to colors, adjust brightness/contrast apply brightness = -10, contrast = 0. Add noise uniform = 6%.

Add a new raster layer (22), go to selections and select 20-strip-4, floodfill your selection with your background pattern. Invert selection and apply a drop shadow with a darker color of your woodpattern. The settings are, offset H & V = 0, opacity = 40, blur = 10. Deselect. Go to colors, adjust brightness/contrast apply brightness = -10, contrast = 0. Add noise uniform = 6%.

Add a new raster layer (23), go to selections and select 21-strip-5, floodfill your selection with your background pattern. Invert selection and apply a drop shadow with a darker color of your woodpattern. The settings are, offset H & V = 0, opacity = 40, blur = 10. Deselect. Add noise uniform = 6%.

Add a new raster layer (24), go to selections and select 22-keyboardshelf, floodfill your selection with your foreground pattern. Invert selection and apply a drop shadow with a darker color of your woodpattern. The settings are, offset H & V = 0, opacity = 40, blur = 10. Deselect. Add noise uniform = 6%.

Add a new raster layer (25), go to selections and select 23-keyboardstrip, floodfill your selection with your foreground pattern. Invert selection and apply a drop shadow with a darker color of your woodpattern. The settings are, offset H & V = 0, opacity = 40, blur = 10. Deselect. Go to colors, adjust brightness/contrast apply brightness = -10, contrast = 0. Add noise uniform = 6%.

Nearly there ! Now we only got to add some additional shading. See screenshot below.

Activate layer 2, select it with your selection tool, invert the selection and apply a drop shadow : offset H = 100 - V = 50, opacity = 40, blur = 50.

Activate layer 11, select it with your selection tool, invert the selection and apply a drop shadow : offset H = 25 - V = 25, opacity = 40, blur = 30.

Activate layer 15, select it with your selection tool, apply a drop shadow : offset H = 5 - V = -5, opacity = 40, blur = 30.

Save your image, merge all layers visible and tube it for further use !!

Now you can start decorating your computer desk :)