The first thing you should do is stop being so critical of yourself. The second thing would probably be to work through the lessons on this website.
I am trying to use lessons but, as a free account, I'm restricted to one a week.
So use other resources. Lichess, for example, has lots of puzzles, lessons and videos to use and study...all free.
your pawns create space behind their advance almost like an advancing fence.
they also help to prevent the opponent's activity by restricting their movements (because the opponent doesn't want to trade their pieces for your pawns, they have to run away from your pawns' attacks).
your pieces (when it's possible to safely go there), can use the 4 center squares, and to a lesser extent the surrounding squares, like a launching pad. you can attack the enemy queenside, center or kingside from the center, whereas if you launch a flank attack you're more limited.
really the best way to play at your level is just to stay solid & active & take the opponent's pieces when they mess up:
after you win one for free, start trading pieces for your opponent's equal pieces.
once you're the only one with pieces, start taking your opponent's pawns.
once their pawns are all gone, start pushing your own pawns.
make a few queens & checkmate the enemy king.
remember these values at all times:
pawn = 1
N & B = 3
Rs are = 5
your Q = 9.