ahhh help with USB cable

[Joolooloo]

So Im recording some home demos for my solo project, and I
know Im not using the best of equipment, but its all I got.

I have a Line 6 Spider III Head with a Madison 4 X 12 cab
and Im using a cable to run out from my amp to a USB port
on my computer. It picks up, and I can record some guitar lines
but as soon as I try to play back anything, no sound comes out.
Im really confused, haha I dont exactly have experience with
home recording, but I would like to start getting into it.

I also have Cubase 4 (but i have no clue how to use it)
Im also recording drum tracks with EZDrummers Drumkit From Hell
with Fruity Loops 8.

Any help as to how I can get some guitar lines recorded?
Thanks guys!

[mjbphotos]

What software are you using to record? Sounds like it is not set up to your output driver/speakers.

[nzausrec]

Check in to your Audio Devices on Cubase - click in the panel the same where the vst's are. Once open look on the right side for your output device(s). It might be set to some wierd thing rather than a soundcard or audio interface.