Hello there! 

Greetings! 

Fist of all one needs to qualify neet for studying mbbs , even for pursuing it in a foriegn country.

In USA you cannot study mbbs i.e. medicine just after completing your 12th . The prerequisite to apply for medicine in the US is different. 

It is not possible for medical aspirant to just have completed the higher secondary school to apply for MBBS in the US.  The minimum entry requirement or the basic eligibility criteria to apply for MBBS is graduation.the students must have studied science courses in their graduation stream.   

The applicant must also become qualified in the MCAT. The Medical College Admission Test determines the ability of the applicants with respect to critical thinking, problem-solving ability, written communication, and evaluation of the scientific knowledge and assessing the overall knowledge.

A good score in MCAT test secures a seat to study MBBS in US.

So, if you have graduation and qualifying MCAT score, the next step is sending the application to the Medical School you wish to study in the US.

Thankyou.