Amanda, have you tried Paint.net? It's free and I've heard many members say that it's the greatest thing since sliced bread
There are a few other free graphics programs that are listed in our
directory as well.
If you just want a button (like the little 80 x 15 size) search for Zappa's Brilliant Button Maker.
As to the rest of it - I'd *strongly* suggest designing a logo with at least Paint.net if not something more sophisticated (I've also heard Logo Creator is great and has been used by many of our VAs - it's about $30)
Have fun playing around with your graphics!