Well, sorry to say, that isn’t how it works. Don’t get me wrong, if you really work at it I’m sure you can do it but you are WAY behind the curve if you’re 20 years old and have done nothing but tinker with BASIC and C. That said here's my advice...
First, accept you need to work day and night to accomplish your goal. Again, you’re already way behind so you have a lot of catch up to do just to be competent. You should be looking at 70 to 80 hour weeks of pure hard work (including your grocery job).
Second, learn Python (or some other language) backwards and forwards before you even start anything else. Tinkering doesn’t prove anything. Anyone can write a "hello world" app but true programmers have to think in a very specific, logical fashion. You might not have the aptitude for that and there’s no point wasting time pursuing this goal if you’ll never be able to get good at it. You can learn everything you need to know with a search engine these days so there’s no excuse here.
Third, stop thinking in generalizations. No one succeeds by saying "I want to found a start up." You need to latch on to an actual idea and you need to start working on it as soon as you are able. From where you live and the experience you have I figure you’ll need to create a whole product just to interest anyone.
Again, I apologize for the harsh tone but I think it’s justified. As rude as it sounds someone who gets in your position usually doesn’t get out. Getting out will not only be the hardest thing you ever do it will be close to the hardest thing anyone’s ever done. You literally have to remake yourself at a time when many of your instincts have already been formed. It’s not easy, it’s not fun and it will be tons of work and tons of time before you see even a little bit of results.
But if you want to succeed you have to commit yourself to that reality.