How to convert class diagram to a database model?

Question

Hi,

I found thousands of examples of how to turn an existing database.mdf into a graphical representation or also real c# classes. But in my case, I have already written classes in c# and I want to create the equivalent database.mdf with it. I am using VS2012 and I tried already all sorts of Entity Models and Linq to Sql stuff. Nothing seems to have the simple function to just translate the c# code into SQL and create the tables..

Much of thanks for helping me out,
Florian