How can i get better at the midgame?

Good Positional Chess, Planning & Strategy Books for Beginners and Beyond...

https://www.chess.com/blog/RussBell/introduction-to-positional-chess-planning-strategy

Improving Your Chess - Resources for Beginners and Beyond...

https://www.chess.com/blog/RussBell/improving-your-chess-resources-for-beginners-and-beyond

more book recommendations and resources in my other blog articles...

https://www.chess.com/blog/RussBell

Simplify chess (google it) has some good material on pawn structures and typical middlegame plans. Its advanced stuff so may not help you win if you are still hanging pieces. But worth a look if you think you want to learn more about planning.

The middlegame is simply an extension of the opening. To learn the middlegame, you should learn your openings well, learn what the strengths and weaknesses of both sides are, and that will hint you towards developing a middlegame strategy.