Taera, I know what you are going through. When I was your age, I had a miserable time with relationships of all sorts, and especially with girls. Looking back, there are a couple of things that might have helped me, and a few things that I did do to help myself, that might be helpful to you.
First and foremost, realize that you are not the only person in your school who feels the way you do. There are others who also feel helpless when it comes to relationships. One thing that helped me, even though I wasn't very good at it, was to seek out others with similar interests and similar problems. For me, there were two places that got me going. One was the chess club and chess team at my high school. Not that I got along perfectly with everyone, but it was worth the effort and I was able to make good friends with similar interests to mine. The second place was church, as again, I was able to find people with similar interests to mine.
While the places to find people with similar interests may be different for you, the point is to seek them out and become involved. Take advantage of opportunities at school. You are correct that you shouldn't sit around and play computer games all the time. You need to get out and do things with other people, even though it takes a lot of work at first.
Now to the more difficult topic, girls.... (and especially the one you are interested in.) I just got a little advice from my wife (yes, even the most awkward of us can eventually find the right girl) about this. The most important thing is to not try and force the issue. I drove off a couple of girls I really liked when I was in high school and college by trying to impress them into liking me. According to my wife, the best thing is to be really interested in her (as a person, not as a girl, if that makes sense) and what she is interested in. If you really like her as a person, she will sense that, and like you back. Whether things ever progress beyond that is not for me to say from this distance, but a strong friendship is necessary for the relationship to ever progress further.
If there really seems to be a friendship developing, then try asking her out to a very non-threatening thing, perhaps an event at school. If she says no, do not push the issue and your friendship should stay intact. Just keep building your friendship when you have the opportunity. Do not make the mistake I made and push the issue by telling her how attracted you are to her until the relationship is much further developed. Finally, if the relationship does not develop the way you want it to, it is not the end of the world (though it may seem like it). You are still very young, and there are a lot of girls out there. I met the girl I eventually married when I was 21, and did not convince her to marry me until I was 27. It took that long to build our relationship, but it was worth every day. I am truly fortunate that I did not get one of the girls I pursued before, as I now realize that they were nowhere near the match for me that my wife is.
One thing that I regret is that I did not talk with my dad much about what I was going through in those years. Later, I discovered that he had had many of the same experiences that I had, and could have given me good advice, had I been willing to talk with him. I would recommend talking with your parents. Chances are they have some pretty good ideas of what you are going through. (I did talk some with my mother, whom I was closer to at that time. It was very helpful to get a female's perspective when dealing with girls. The most important thing I learned was that they are just as insecure as the guys are.
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