what do i need for my mic in my band?

[dante]

For a mic get either a Audix i5 or Shure SM57, can't go wrong with any of them, they are both $100 though. You have to get and XLR to 3.5mm converter cable to connect the mic to your computer to record. You will have to get a recording software, a free one but not very good one is called Audacity. A good beginner one that is very easy to use is called Mixcraft 6 but it costs like $70.

Bottom line: recording is not cheap if you don't have a job or someone capable of buying you this stuff.

EDIT: You can't just use any mic, buy the ones I talked about above, they are made for this and are the 2 most popular guitar amp recording mics in the world.
EDIT2: Oh and if you wanna get even more technical, you might even need to buy a pre-amp which amplifies the sound of the mic, because the mic by itself usually emits a low volume signal when recording that is not loud enough.