First of all you are adorable and you don't realize it. You have great eyes and an awesome smile. What you lack is not in your body it is in your confidence. They gym will help but confidence comes from the heart and it can be built. Secondly, if you want to win a woman.. any woman, no matter how beautiful.. all you have to do is three things 1. Make her laugh, often. 2. Let her know she is special to you and all you have to do is listen closely and be truly engaged in conversation. 3. Know your own worth, you are a good one and she will see that if you will see that.
Many girls, including very attractive ones, fall for "ugly" guys. Personally I believe personality is key to attractiveness. And in all honesty you just have to find the right girls; ones who will be attracted to you based on your talents and attractiveness, not your looks.
If you want to improve physically just try to clean out your diet and work out. It is amazing how big of a difference muscle can make. ;)