Ok so im working on a recording just messing around with ideas, and I need drums right? right.
So, I decide to add them in with midi, utilizing the GM Drum Set (oh yeah good sounds lol).

The problem is, that I can't here them when plugged into my Audio Interface, I have to be plugged direct to my Laptop headphone out. How do I get the midi audio to come out of my interface headphone out? or the real instruments through the computers headphone out? I would like to be able to record more parts and listen to the parts I have already played.

Gear List:
Native Instruments Guitar Rig Sessions I/O
Cubase LE 4
Bome's Mouse Keyboard
Guitar/Bass/Other instruments in general

I have no moniters, just headphones to work with, how do I get everything to come out of the same headphone jack?
If you all need clarification just let me know.

Thanks in advance.