I did not go look at your scores, don't really need to. You are new, there is a learning curve to get better at this game. The scoring system may seem really screwed up at first, but it boils down to earning points per second. If you throw misses, you are not earning points. If you are taking a long time to shoot the stage, you are getting too many seconds. Either scenario will lower your scores. Whoever has the most points per second, wins. Everyone else is graded on the curve set by the winner.
Now how to get better, in my opinion, get involved with all aspects of the match. Make friends with the people that set up and run the match and pick their brain about how and why they do things in the match. After you have made friends, ask for advice. Chances are they will give you good advice and coaching. The more you learn in the next few matches, the quicker your scores will go up.
Good luck
Scott