I have been playing chess for a while now, but have only recently found chess.com. My score though is extremely low (like 541). I never seem to do well and always end up losing games. Is there some fundemental principle I am missing, or do I just suck?
No you do not suck.
I am definitely not a good chess player(far from it) but just looking at your last game on 29th Feb you just made a couple of mistakes that contributed to you losing.
For example -
1. Early in the game you failed to take the opponent's Queen with a pawn when it was a fairly obvious move. He made a bad move and you missed it. Happens to all of us occasionally. Always take your time so you do not miss things. Maybe play 15 min games so you can think more about your moves.
2. Later in the game you allowed your opponent to take your Queen to save another less valuable piece. Always save the most valuable piece if you are faced with that situation.
Practice on this site against the computer.
Anyway, it's just a little board game (which does NOT matter) so just play and enjoy it and please don't allow yourself to get frustrated.

I have been playing chess for a while now, but have only recently found chess.com. My score though is extremely low (like 541). I never seem to do well and always end up losing games. Is there some fundemental principle I am missing, or do I just suck?