Both of these hands should be folded preflop. Also the line of bet, check, bet in hand 2 looks really suspicious when the river card doesn't really change the dynamic of the board.
Both hands are very clear folds pre. There’s a huge difference between 76s and 76o. In both hands a 3 bet pre would be ok if you had 76 sooted (although still quite wide and I’d lean towards folding 76s here until you have some more experience)
Don’t donk in hand 1. Basically I’d never donk (ie bet OOP into the pre flop raiser) heads up against a reg.
Hand 2 - don’t min 3 bet. 3x the raise is a good rule of thumb when you’re in position.
When you bluff you need some amount of fold equity (ie villain(s) will fold a decent amount of the time) and/or pot equity (ie we have a chance of winning when our bluff is called, say if we have a draw on flop or turn). You basically have none of the latter in either hand.
You need some work on the basics. Look up some good preflop ranges and stick to those to start with. I’d recommend The Grinder’s Manual if you learn well from books.