Tips for beginner

Any tips for me as white? The game was quite passive at start, I am not used to it being at such low levels, where players are quite aggressive and blundery. Finally won because black blundered their bishop and resigned couple of moves later.

Sidenote: this was my first en passant ever.

4 dxc5 would have given you an advantage.  He couldn't have taken back without letting you trade queens and leave his king stuck in the center.

You learn more from analyzing your losses.

Black gave away a piece with 16. .... Bh6 and you took full advantage. 

Black gave away another piece playing 19. ... Qxd7 instead of Nxd7. You took advantage again. 

You played well. 

You might learn more b asking for advice about a game you lost. It seems to me that you played this one perfectly well.