[Drego the horrible]

I noticed that if my characters level up that the amount of hit points they get changes each time I reload and level up again. How is one supposed to know the max number of hit points a character should get. Also, I dont understand this hit dice thing. I have no idea what a hit die is to be quite honest. Can somebody please break that down for me. I am in need of help here. This is my first game like this. Oh, yeah I would like to give a shout out to my boys in DC! One love.. And Big Mike... I know you in lock down but we gonna get you out of their.. Stay strong brother... Keep your head up...