Take your guitar cable, buy a little radio shack 1/4" --> 1/8" converter, plug your guitar into the line-in/mic-in on your computer (unless you have some sort of an audio interface/outboard soundcard etc...). Then the rest is just tweaking the settings on the computer and the program to recognise the input signal (i.e. make sure everything is fine under Volume control --> Options --> Properties --> Recrding in Windows, etc...)