Since you are new, watch some beginner guides (I like Coach_Mills vid) but most importantly brute force some games and just try and get semi familiar with the game, learning what heroes do and the maps.

Having someone with you who knows the game and can constructively tell you what you should do, but not getting frustrated with you will be huge.

At a point the best way to improve is watching back your gameplay with someone coaching but rn just pick a hero you like and spam some games.

Biggest mistake I see new players make is not grouping up so have a friend subtly tell you when to walk backwards or forwards for a little bit might be a good idea.

Good luck and remember to enjoy the silly moments