How to add a user manually with different group using FBA

Question

we use both code like java and SharePoint.In java side,we make registration and login page and those user data are send to active directory and then we get user name and password  on login page of C# coding and its share to SharePoint,but automatically user are not to with different group.we need to add manually for each user with specific user.....can u help me how to get the user with different group in SharePoint 2013.

 

 Thinks:

java for registration and assume role

Sharepoint FBA memeber ship are using for login the user

 

 

 

 

Advance in thanks