Custom forms authentication in MVC

I want to use authentication on my site in order to login to the Admin section. I already have my database schema, I don't want to use the ASP.NET membership tables for SQL Server. I have three tables: Employees, Roles, and EmployeesInRoles.

I'd really like to keep this as simple as possible, but I'm having trouble finding a solution. I just want to use forms authentication with my tables so employees can log in, log out, change their password, etc.

If anyone could direct me to a blog post or tutorial about this, that would be great.