Play more Chess, dude.
How to get better at chess as a teenager?

watch this it will help a lot
http://cdn.alltheragefaces.com/img/faces/large/misc-are-you-fucking-kidding-me-l.png

Practice Practice Practice. Also, check out http://www.chesscademy.com/ There isnt alot there yet, but there are a few lessons and drills you can run, and its all free.
I have been watching lots of videos and playing lots of games. I have only really been trying to get better for the past 3 months. Anyone know how you can get better?
If you want to get better and learn Chess you have to roll up your sleeves and work really hard that's what Rubinstien did after reading the book Chess Checkmate by Sossisnitz he absorbed all it's contents he joined a Chess Club and would lose alot but he kept at it he kept working hard paid his dues and became a great player.
Nothing is free or easy no pain no gain so study hard crack the books open up a real chess board and study practice against good players who have fighting spirit and give you a tough game all the time.

watch this it will help a lot
http://cdn.alltheragefaces.com/img/faces/large/misc-are-you-fucking-kidding-me-l.png
http://a.abcnews.go.com/images/US/gty_leader_kim_jong_il_ll_111221_vblog.jpg
Just leave

I agree with most of the above mentionings. The "fastest" way to learn for me, has been studying my own games, finding my weaknesses, and trying to either avoid my weaknesses, or learning how to deal with them.
Second mention, for seriously improving your games, is to play correspondence chess. This method is much slower, it can take days, or even weeks for a move. But in between moves, you scour books that relate to the current game. You study the position and determine its weaknesses, you play different variations of the game out on a board figuring out why a move might be considered bad 3 or 10 moves later (this is especially true of pawn moves as creating a pawn weakness is inevitably a long term problem because pawns can not move backwards)
Many players dont enjoy correspondence chess, and that is okay, but if it works for you, then make sure to keep a notepad, write down all your ideas, for each and every move. Consult your notes as you review the games, and above all, enjoy yourself. :)

Study tactics, tactics and tactics. Winning chess tactics by Yasser Seirawan is a very good book. Practice what you learned from the book in tactics trainer and chess tempo.

If you want him to leave, then block him. He won't be able to post anymore.
I dont know how to block people
Find a chess club nearby and join. The club will almost certainly have teams which play in local leagues and week end congresses. After you have been attending club nights regularly for a couple of months let the organiser know that you are interested in playing for the club. If they run a team playing at your level that will get you on it. If they only run one or two teams the organiser will tell you the standard you need to get to in order to be selected. You then work towards that.
There are two points to this. The first is to get into playing chess face to face ("over the board"). It is a slightly different experience to playing online and more fun. The main point, though, is to get into playing representative chess. That is quite highly motivating. You want to do well for yourself and for your team. Analysis after a game (with team mates) comes very naturally and a keen team will arrange training sessions.
I have only very moderate abilities at chess and have improved only very slowly over the years. Playing for a team, however, has kept my interest alive down fifty years. Have a go and I suspect it will help you attain the level your talents allow.

Try chesstempo.com, it´s free. Do the Standard tactics problems, there´s no time pressure, and you should start seeing the chessboard differently ;) and it´s fun!

@AndyRichter: some people hide their stupidity. You don`t. I agree with Max and many others, get lost!
I have been watching lots of videos and playing lots of games. I have only really been trying to get better for the past 3 months. Anyone know how you can get better?