So I go to GC to get a mic. I was going to get a Shure SM57 and the guy there told me that it was "Ok" considering its been around for 40 years but for the same price I could get somthing less muffled with more bass and more wind resistant called the Audix i5 so I went for it. Now I have not mic'ed an amp before and I tried today and I put the mic against the tolex like it said but when I recorded I got a sound like someone is speking too close to a microphone with too much bass. What am I doing wrong?
i dont know the mic, but i do know that the sm57 has a proximity effect. basicly this means that when your sound source is very close to the mic, you will get a bass boost. dont know exactly what causes it, but my manual says it happens in unidirectional micrphones, which i assume that you have. basicly i would start by moving the mic back to about 4"- 6" and see if that helps any. if not, just EQ the amp to have less bass. you can always cut down the bass using the EQ of your mixer or recording program as well.
You should place the mic about an inch away from the tolex. Just enough so that it is not pressed up against the front of the amp. Position it so it is about half-way between the outer edge and centre of the speaker cone (the closer to the edge you put it, the more bass you'll get). Then play around until you get the sound you want.

You could also try angling the mic slightly so it's not pointing straight towards the speaker. That might help cut out some bass.

Good luck, and let us know if this helps.