My alternator and belt get really hot when I turn it on almost instantly. Anybody know what this could be or what I need to do?

 

My guess is a failing alternator or the belt is too tight.
Remove the belt, spin the pulley. Feel for rough or resistance in the pulley rotation and listen for noises. You can also attempt to wiggle the pulley. If no play, no rough spots, take it off the car and have them bench test it at the parts store.

That is where I would start.