What to do if i cannot join with hepatitis b. i have hbsag. does that mean i have hepatitis?

Become informed: I am going to assume you are a lifelong hepatitis B carrier. Nowadays in the era of immunization it makes little sense to exclude you from military service or some other career path because of your status; you do need lifelong health care to prevent complications and they probably don't want to spend the extra money. Find some other career you can enjoy and learn about your situation.