hello prakash ji, there is no such thing like MBBS in usa. 10+2 is high school equivalent in usa. after your high school, you need to do 4 years bachelors degree. if you are already decided going for medical doctor then undergrad with major focus in biology, chemistry, microbiology, ... basically pre med subjects will help you a lot later in your graduate school. after your four years bachelors degree and good MCAT score, you might get into medical school and it takes 6 years after that to become a doctor. it is very difficult to get aid and admission in medical school if you are not an american. however once you are done with 10 years of education after what you have now that is 10+2, you will have a very good income. good luck. on flip side, it is good idea to do MBBS in Nepal/India and take USMLE test and come here for residency, which is cheaper and easier way to become a doctor in usa.