Question : 3 colour gradient for my shape

I want a shape that starts as colour black, then through to yellow and finally through to white of about height 800px to be used as a background for my website.

Can someone give me some pointers on how to go about getting this done in photoshop cs3?

Answer : 3 colour gradient for my shape

here's a very good video tutorial that explains what you have to do

http://tutorials.ausweb.com.au/web/Tutorials/Photoshop-CS3-Video-Tutorials/Photoshop-CS3-Tutorials---how-to-use-the-gradient-tool