If you don't know how to weld I wouldn't reccomend a snowboard box or anything structural for your first project. See if the shop teacher can help you. Welding isn't exactly the type of thing you just pick up and do first try. You will be arc welding though, whether it is Mig, Flux, Stick etc. to answer your question. You will be welding on mild steel. Mig or Flux core would be your best bet because it is the easiest to learn.