TxHealer

Forgive a terribly newbish question. I'm trying to encode some wavs I have made into MP3 files. I've never had the joint option come up under stereo before. What is the difference between joint and stereo? I need the left and right speakers to be treated individually (ie I need several instuments to only be present on the right side and not at all on the left- which is how the WAV is recorded.)