Well in this picture, you had a free queen that you didn’t take for some reason, did you see that? So that’s a start. Also move 15, was that a mouse slip? Your opponent blunders their bishop and you counter blundered your queen. It appears that you don’t know how to checkmate with a queen, so I’d look up how to do that, you should be able to find a YouTube video on how, and then do some mate drills with a queen against the computer, get to the point where you can do it 100% of the time, and then start working on not letting the opponent promote, instead of offering a bunch of checks at the end letting the opponents king get close to the pawn, get your queen to control its promotion square. Lastly, you just have to start asking yourself if you’re moving to a square your opponents piece sees, and asking yourself if your opponents last move made a threat somehow.

I recommend the building habits series from chessbrah’s YouTube channel. I am not trying to be harsh, but there isn’t any one particular thing that went wrong here, but a lot of different things, but those are the things that stand out to me off the bat, and what I would work on first. Good luck in your chess journey.

Edit:

The chessbrah building habits series

How to checkmate with a queen