How can i use the roles from fba 2013

I want to control access to sites with sharepoint-rights and the FBA roles.
However, I find no way to use the roles of FBA with the rights in the SharePoint.
What am I doing wrong?
Many thanks for the help.
You should be able to assign permissions to roles and add roles to groups, just the same way you do it for users using the people picker. If it does not work, you likely have something misconfigured in your web.config.