How to implement Repository and UnitOfWork Pattern with code first EF 4.1 Existing Database

I'm new in Repository and UnitOfWork Pattern, and i do not know how to implement Repository and UnitOfWork Pattern for my data tier. For Example : i have three tables role, user, userInRole, it means i have three class in Data.Model and three class in Data.Repository right ? but if i already have existing database with three above tables how do i write code my data classes, model classes to using these tables in Database SQL Server 2008 (because the server that i rented which are not supported SqlCe) with Cod开发者_JS百科e First EF 4.1. please give me some example to implement repository and unitofwork pattern using code first EF 4.1 and existing database. thanks in advance !

I would check out the MyFinance app on CodePlex. Should be pretty much exactly what you're looking for.