I honestly don't go into the "Newcomers" section nearly as often as I should, so I never saw your initial post. However, after I read your above post I went back and found your original introduction. After reading your first post I have a few things I feel the need to say...
1) You did have two people respond, so SOMEONE was trying to help. Was it the advice you wanted? Were they flawless words of wisdom? Probably not. However, people were trying to help and I just don't want them to go unnoticed.
2) One of the responses to your first post included a piece of advice that I will echo - talk with your parents.
I'm a parent of two children myself and, this may sound harsh, but I have no other choice than to be as blunt as possible - how in the HELL did your parents allow you to become so heavy and unhealthy? Dude, you weigh 500-plus pounds and you're only 15 years old? That is absolutely insane, man. Absolutely insane. I know that is coming off as mean, but I'm not trying to be a dick about your weight. It's just that, in many states, your parents allowing you, aiding you, assisting you in becoming so unhealthy is considered serious enough to be labeled as child endangerment. Your condition is serious. Not only are your parents possibly in a position of legal backlash, more important, your health and your future is at stake.
I'm glad you made the decision to come get help. You need it. None of us are in any position to judge (as we all have our own health-related issues with which we have to deal) but we are all in a position to help. So, I'm glad you came here.
However, you still need to talk with your parents. You're still very young and you should develop some sort of game plan with your parents as your journey might need the inclusion of doctors and medical professionals to help guide you in the right direction. Which brings me to the final thing I wanted to say...
3) You mentioned in your original post that you went to the hospital a few weeks ago. Did they offer you any assistance or information at all in regards to losing weight? If not, go back and ask for help. I work at a hospital and I find it extremely odd that they would just send you on your way, so hopefully they left you with SOME sort of information.