Also, hook your monitors to the main outs on the mixer. Make sure you have the sound card input selected as the source for the track in cool edit. If it still doesn't work, and you are using an regular computer soundcard, open Windows Master Volume icon in the system tray, select Options and Recording, and make sure that the line in is not muted and that the volume slider is up.
No- bring the outputs from your soundcard to two of the line level channels (or one of the stereo channels) of your mixer. If they go to separate channels (vice a stereo channel), then make sure you pan the channles hard right and left and assign them to the mains output (assuming that's where you monitors are hooked up)
"I can only record 2 at a time?"
Yes- you can treat the left and right sides of the stereo line input on your sound card as two seperate channels. for instance, if you wanted to record two guitars at once, run the source to two channel strips, assign them both to the ALT bus, pan one hard left and one hard right. On the recording software side, set up two audio tracks, one with the left side of the soundcard input, the other with the right.