Login through unity to an online database (SMF encrypted)?

Hi everyone I'm making an fps online and i would like the executable to allow users to log in from the executable and access their accounts that are stored on my database (using SMF, passwords are encrypted by SMF). How can i do that? I don't know how to access the database from the executable neither to log in from there.. I bet there is a way to do it because a lot of games have got similar things but i really can't get it. Can someone explain me this please? Thanks in advance. Ninja