A lot of what you find on line for Photoshop might not work with 6.  :(  Check carefully for disclaimers about which versions are supported by what you're looking at.  You might find that in order to do anything with plug-ins, you'll have to upgrade to CS3 or better at this point.  Not good news, I know, but there aren't many filters made any more for a program that old.

The good news is that there are a lot of things you CAN do with 6, and there's plenty there to learn!   

"If your pictures aren't good enough, you're not close enough."  ...  Robert Capa