Photoshop brushes.?

I have hundreds of brushes downloaded, and until now they've all worked with perfect ease, but now they just aren't showing up. How do I change the colour of the brush [is it just the same as the foreground and background or is there a different tool for that?], and should I create a new layer when I want to put a brush onto a graphic or piece of work?

Or am I, in fact, looking in all the wrong places and destined to go nowhere?!

I'm using Adobe Photoshop CS3 Extended, by the way.

Photoshop brushes.?ariel

Okay well, yeah I'm pretty sure when you want to change the color you just use the same one. Also, you really should use another layer for brushes, just incase you get far along then decide you want to change a brush or get rid of it you won't have to delete everything else you did.