Rainbow colored text

Okay, well I just made a new image with my name written all over it. What I'm trying to do, is color the text RAINBOW colored, and so it looks blended together.
Is there a way to do that with the paintbrush tool? And then just go over the text, letting the paintbrush do the work? That seemed the most logical to me.
I'm pretty new at this, so I'm not QUITE sure what I'm doing so far.

Please let me know how to do this!
Thanks,.

You can CNTL click the text layer so you only have it selected and use the gradient fill. There is a rainbow preset in the gradient pallette try that and see if thats what you are looking for. Let me know I might have some more sugestions.