The AudioBox USB will (basically) function as your computer's sound card when connected via USB. The AudioBox USB converts analog audio to digital audio and vice versa, so you can record to and play back from a computer.
So once you've got it connected, it's as if the 2 input jacks on the front were input jacks built in to your laptop. That's kind of a watered down explanation of what all is happening, but I hope it helps.