I'm assuming you know how to create new layers and use the "dotted rectangle" selection tool.
1. Create New Photoshop Document
(assuming most folks see web pages on 800 x 600 monitors, make your document size about 780 pixels wide by 410 pixels high - which is all the space you have left after discounting the browser buttons and scrollbars)
2. Make sure you can see your LAYERS palette. (usually on by default, if not: go to WINDOW menu and select LAYERS)
3. In LAYERS palette: Double-click on the BACKGROUND layer to unlock it and hit OK to turn it into Layer 0
3b. I prefer to hit (CTRL+A) to SELECT ALL and then hit(DELETE) to clear Layer 0 and make it transparent.
4. Now go to the toolbox and get the rectangle selection tool (top-most left corner tool). Select top 3rd of screen.
5. Now go to toolbox and click on the foreground color to launch the color picker. Choose some color you want to make as your first "color band". Hit ok to quit the color picker.
6. Select the PAINT BUCKET from the toolbox (sometimes it hides beneath the GRADIENT TOOL) (keyboard shortcut: hit the (G) key)
7. Click the paint bucket inside the selected area of the document to paint it.
8. Hit (CTRL+D) to deselect (dotted lines will disappear)
9. Go to the layers palette and Create a new layer. (named Layer 1 probably)
10. Repeat steps 4, 5, and 6 to create the 2nd and 3rd bands of color.
11. Now that each band of color is on it's own layer, you can adjust color strength of each band by playing with it's OPACITY settings in the LAYERS palette (FUN!). With the GENERAL SELECT (black arrow) tool from the toolbox you can select individual layers and then move the colored bands around if the position of each band was not perfect.
12. Open up your logo in a seperate Photoshop document. (CTRL+A) to select the entire logo, and hit (CTRL+C) to copy the entire logo. Then make the new document active and (CTRL-V) to paste logo into the new document.
13. Logo will come into the color-band document on it's own layer. Go to LAYERS palette and drag new logo layer to the TOP MOST layer (I realize if it was on a WHITE background it will block out a lot of hard work you just did on those colored layers)
14. Play with the BLENDING MODE of this logo layer in the LAYERS palette. The BLENDING MODE is a menu that is found next to the OPACITY setting. It is usually set to "Normal" but you should try setting it to "Mulitply" or some other option to make the white background disappear and let the colors show through. You can then, also, adjust the OPACITY for a nice watermark effect.
15. Other special effects can be applied to the LOGO layer by RIGHT-CLICKING on the logo layer and select "Blending Options..." - play around in the resulting pop-up and hit "okay".
Hope this helps...
