Welding Differences-MIg TIg



So Im considering taking a welding class over summer. I wanna use it for mostly my bikes, go kart, and random metal projects.

I have the optiion of taking Shielded metal arc (SMAW)
or...Gas metal arc (GMAW or MIG)
or even Gas Tungsten (GTAW or TIG)

I know very little about welding or the different kinds so if someone could tell me which class would help me most for welding mufflers, headers, frames, and mounts, and also what the differnt kinds of welding are used for... that'd be very helpful. :D