How do I install an alternator belt on a 1977 cutlass supreme?

Loosen the two bolts at the top and bottom of the alternator until you can move it on the bracket. You may have to take the power steering belt off first to get the alternator one on. Position the belt in the proper pulleys and then using a huge screwdriver or a wheel wrench pry carefully against the alternator pulling the belt tight until you have a bout half an inch of deflection when you push on it. Tighten the belts and do the same to put the power steering belt back in place. If its your first time doing this it will probably help to have a helper as well. Things are a bit awkward to get at and its definitely easier to do if the engine is cold. Take your time, and good luck.