Beginner wants to compete in tournament in 10 days
Solve tactics problems here or another site. Search kingcrusher's videos at youtube. They are instructive. Matojelic's videos are also instructive. If you don't know yet how to mate a lone king with rook and king, you can also search that at youtube.
Thinking tips:
Always study your opponent's last move
Always look at the whole board
Before you make a move, check if there is a tactical drawback
Goodluck and enjoy your tournament. Don't let setback discourage you. Learn from it.

I would just play as many 10 minute games as you can in live chess.
While playing is essential, studying is also important.
10 days isn't a lot of time to learn so don't cram to much and expect great results. Rather, start learning the fundamentals and use these 10 days as motivation to begin serious and systematic learning regimen for yourself and watch your chess improve because of that. Have fun at the tournament! Make sure to post your he games here for review.