Any tips on improving this game


About developping the pawns: I'm not quite sure what you mean. Usually we speak about developping during the opening when a goal is to develop all your pieces into the game and pawn moves are usually good at this stage only as long as they help you to develop pieces or contest strategically important central squares.
About your opening: First few moves were fine but avoid moves like 5... Bd6 which blocks the d-pawn. There is a good chance that you want to move that pawn in the near future in order to allow Bc8 to enter into game. Better would be 5... Be7. Also 4. Bb4+ is a check that doesn't really achieve anything - better 4... Bc5 or Be7.
In general, I can think of two things that should improve your game a lot(by the way, this is true for almost all beginers). First is getting rid of the easy tactical mistakes (For example instead of 35... Kxe8?? better would be 35... Qe6+ (with a check!) followed by Kxe8; 26... Na3+?? should just drop a knight if white sees 27. Bxa3 and therefore it would be better just to move the threatened queen (eg. 26... Qd5) etc.). There is no easy cure for this except playing a lot.
Second thing to really concentrate on is to remember to use all your pieces. For example in this game you still had your rook in a8 and bishop in c8 completely undevelopped at move 20. These are powerfull pieces and the failure to include them usually results in a loss against skilled opponent! Therefore you should really think very carefully during the opening how to include all your pieces (except pawns and king!) into the game as quickly as possible. You may also benefit from observing how experienced players do that in their games.