I can get sound in the computer with the computer mics, but from there it gets messed up. I've been trying to find out what kind of equipment and stuff to get but i havn't been able to figure it out. Do i need a special soundcard or will it use a basic one that comes standard in new pc's? (I have an hp pavilion) What should i get to plug guitars and mics into my computer. (I mean something like those line 6 ones for about 100. something of that nature) and i tried plugging in my sm57 with an adapter or a regular input, but when i do that, it isn't very loud at all and the sound only comes through one speaker.

Any help is really appreciated!
From your post i think what your looking to buy is an audio interface for your PC/Mac. This is the kind of product you might want to look at, that connects to your PC/Mac via a digital connection such as USB or Firewire (Slightly preferable to be firewire due to some small advantages.

Also, you generally dont connect mics straight up to the pc input if you want to get a good clean signal. An interface like that will allow you to gain the input, remedying the problem of a weak signal strength.

P.S Dont take that interface link as a recommendation, it was just the first i happened to find that was generally what you want.