newbie doesn't understand why I've been declared a loser


This game? You've lost the game on time. When your time is up, you either lose the game or it is a draw if he doesn't have sufficient material left on the board to win by checkmate. Your 10 minutes ran out, so you have lost the game. If he had only a minor piece on the board or just a lonely king, it would have been a draw due to insufficient mating material, but here he can theoretically win with what is left on the board, so you've lost.