Okay, first things first. Apply for a greencard. I know it's a long process, it's expensive, and it's very invasive but do this first. People assume they don't qualify and don't even bother asking. But the US still has the highest immigration of all countries, only the UK is a distant 2nd. So obviously, people are getting in everyday. Now, contact the US embassy in your country. Get all your paperwork together, set a…
You should only apply for a visa when you are reasonably sure you will get it (i.e. have an offer of employment, funds or family to sponsor you).