Scanlines/Grids

Hey all, just a quick question... I'm trying to create scanlines or a grid in the background of my image, BUT, i've never used any tools, and have no idea how to do it. I've searched around a little, and can not seem to find it. If anyone can tell me how to create them, or insert a link to where i can find them, i would be greatly appreciative. Thanks in advance!

Here's a link...

http://www.thinkdan.com/tutorials/photoshop/scanlines/index.html

If you want a grid, just draw a grid pattern instead of the scanline pattern.

ok, thanks for all your help!