Plug a USB cable into the 2.0 USB port of your computer. If your computer does not have a USB port you can substitute the USB cable with a firewire cable. Firewire is faster than USB but not as common. If you own an iMac, your computer likely has a built in FireWire port. If you opt for a Firewire connection, the audio interface also needs a Firewire connector.
Plug the other end of the USB cable or the Firewire into the Audio interface. If you do not plan to use software that simulates an amplifier and speaker cabinet you must use an audio interface that acts as a simulated amplifier. For example, the POD XT, Digitech RP1000 and the Vox Tonelab all have built in electronics that act as an amplifier. If you are planning on using software, using a basic interface like the M-Audio Fast Track Pro, MOTU Firewire or the Presonus Firestudio Project will do.
Plug the guitar cable into the guitar input jack of the audio interface This is typically located on the front of most audio interface units. However, it is possibly located in other areas. Inspect the unit for a ¼-inch jack labeled as instrument input or guitar input. Plug the other end of the guitar cable into the guitar.