Yes graduation from any private or government institute which provides a valid degree for graduation in any stream is valid for doing post graduation program of MBA.

You can give various exams like CAT, XAT, IIFT, NMAT, SNAP, MAT, CMAT, CET and GMAT for enrolling yourself in different colleges.

If you are starting your preparations right now then start making your basics strong first by going through various books like Arun Sharma, reading novels etc. Then once your basics are strong you can start attempting mock papers and analyse them in order to overcome your mistakes and come up with a strategy to attempt your paper which will definitely help you in improving your marks and percentile.

All.the best for your preparations!!