good opening, 7...e4 gave the center away.
10. f5 defends pawn, but opens vulnerable line to king.
11. Rxd8 is better, using the open line.
18. Bf6 trade gets your rook away from the action, if you wanted to trade, earlier was possible (17.)
23. exf3 frees his B, maybe something like Bd5 is better?
24. Rc8 for example or anywhere, here and earlier you make pawn moves which are not neccessary, it's better to develop rook a
25. h5 did it for you
26. Bc4, he could've traded, trading is not good when behind on material.
endgame. you could have tried to take his pawns, making his bishop advantage 0, ang making draw.it was lost, 36. Ke4 could have worked if your opponent blunderd.

In general, I think your loss was mainly decided by the blunder with the rook.
Besides that, you should focus on opening ideas like the center control, the open file was yours to take, but because you were busy with pawns, your opponent took it, getting him the advantage of an attack.
You also waited too long developing your a rook, leaving you the greatest disadvantage. He managed to double his rooks on the file without response, his bishop was freed without problems.

Your opponent had 11 Qb3+ Kh8 12 Nf7+ winning the exchange.

Rather than 7. e4 would a better move there had been bf4?

weakness: failure to spot hanging material.

15. ... Bxa2 wins a pawn.

21. ... b5 gives up the defense of the c6 pawn.

25. ... h5 misses the attack on the a8 rook.

17 ... Bxf2 looks interesting. Did you play through this line? You should have. Chess is lots of hard work analyzing lots of lines. Treat it like a job!