if you just want to do guitar, they sell a lot of usb interfaces thet you plug in to your computer, most of them come with software. If you want to have more options like recording vocals, drums, ect..... then there are so many diffrent ways to record that you would have to be specific on what you would like to do. I did a lot of internet research and bought all the books about recording at the store. good luck youve got a lot to learn.

Hoping that I am not breaking any protocol but, if you are new to recording, you might find this Guide helpful: http://www.tweakheadz.com/guide.htm