Hi,
thanks for writing in.
Presence of HBsAg in the blood suggests viral infection. This needs to be corroborated with the liver state. If there is evidence of active inflammation in the liver as confirmed by biopsy and enzyme levels then a course of antiviral therapy will work. Otherwise antiviral therapy will not be of any help. You need to be careful not to suffer from any further viral hepatitis infection in order to safeguard the liverr function.
With regards

You should get a few other labs checked if this has not been done, including your hepatitis B viral load. You need to get an imaging of your liver (ultrasound) to make sure you don't have cirrhosis. Your doctor may want to do a liver biopsy as well depending on the results.
There is treatment available for hepatitis B, which is very effective and brings down the viral load in the blood to undetectable levels within a few weeks - months. To get rid of the virus completely is more difficult, but again to keep it under control is easy. The treatment consists of one pill a day, with minimal chances of side effects.