What am I doing wrong?

In your game against Johnfiedler1988 you played at 900 level, which is expected of a 350 rated player. You should learn a new opening because you only have a 48% win rate with the queen's pawn opening. Also, don't start a 15-minute game and make every move within ten seconds. Stop and think. Dont just look at your pieces, look at where your opponent's pieces are aiming. In the 300 rating range, blunders are very common. Instead of thinking of risky attacks, only focus on playing well. if you try not to make mistakes, your opponent will probably blunder and do all the work for you. You can't be too defensive, and you can't be too aggressive either. when a move is made, look at the square the opponent's piece is targeting, see if any other pieces are doing the same, then see if your pieces are where they need to be. Then look for checks, threats, and captures. Try doing drills and puzzles too.

Hey.

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I see.. thank you,I will try to implement what you said..

Improving Your Chess - Resources for Beginners and Beyond

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

try chomping on hanging pieces

You are throwing away pieces because you play semi-random moves without thinking.

Look at this game:

https://www.chess.com/game/live/124181340463?username=itzmekpv

On move 4, your opponent blatantly attacks c2, and you ignore it, losing a pawn and an exchange and castling rights.

On move 11 you sacrifice a piece for no reason.

On move 13 you simply blunder your queen.

All that is caused by fast play. You started the game with 15 minutes, and in the end of the game you had 14:46 remaining. Don't do that. Don't play random moves. Use your time and think. Try to find good moves.