Soo, me being the dumbtarded dummy i am and liking to waste money on things I'll never really be able to justify having, I went out and bought a Shure SM58 in the hopes of doing more of my craptastic vocal covers. Anyway serious times, I know absolutely nothing about how to set this thing up, I intended to use it on my mac but I don't know what I need to get to be able to plug it in, i have tried googling it but it just keeps taking me to sites that are selling the microphone, If anyone can shed some light on this I would greatly appreciate it

You need a soundcard and an XLR cable. And the software to record sound but you probably have that. Popfilter could be a nice thing too. When you plug it in, make sure you don't gain it up to high heavens, be certain the input is not clipping (going over 0 dB in).

What do you mean by sound card? I remember a while ago reading about something like an Nbox or and Mbox, is that what it is

Yeah like, a M-Audio soundcard, or Audio Kontrol 1, or whatever. Basically an external soundcard that you connect via your USB port. They differ in size and quality in preamps and stuff. So maybe a small one with one jack/XLR input would be suited for you.

Something like this

http://www.thomann.de/gb/maudio_fast_track.htm

EU

http://www.musiciansfriend.com/pro-audio/m-audio-fast-track-mkii-usb-audio-interface/703669000000000

US