You can do this with n-Track...but it's overkill to some extent. Any wave editor will work.
Just think logically. There should be some sort of LINE OUT on your stereo, and there is a LINE IN on your soundcard. That's really the only connection you'll have to make and it'll probably be RCA to 1/8". No big deal, head down to Radio Shack.
If there is no line out (or "aux out") on your stereo, you could get away with using the headphone jack. This is a harder solution because you'll really have to watch your levels. Don't turn the volume up too loud.
Basically this process will be the same as hooking a mixer up to your computer and recording your own music. You'll be recording wave files of course. Expect to use ~11MB per minute stereo. Record each song to its own wav file. Once the songs are on your HD you can burn them to CD using your favorite CD burning software.
Play around until you get stuck, then ask more questions!
Slackmaster 2000
