Modify existing membership JAR App to work at 2 location

I have a piece of java program which I use to keep track my membership activities, includes adding new member, editing, recharging membership and use their membership balance. It is running on my front desk computer using Access database, however, now I am trying to expand to second location, I need to move the DB to server and modify the software so both store can access this data at same time, and using the same data. Should be pretty straight forward.