Got my new recording equip, few questions.

[neophyte]

Hey guys after all your help I ended up buying a Tascam US122L interface and a pair of MXL mics. So far everything is going pretty well and the sound is great. I do have one question though. Im using audacity and when I record in stereo mode with one condenser mic plugged into my interface, it only records on one side... so basically the one side(left channel) will be recording and the other(right channel) just stays as a flat line. Im curious if this is how it is supposed to be? So what would I do after laying down the guitar track and then when it comes time for the vocals it would lay down the same way on the left channel.

Can anyone explain how they record and lay tracks together? I plan to record guitar, then wear headphones and sing over with the vocal track... Im a newbie