// The Entity base-class is provided by MongoRepository
// for all entities you want to use in MongoDb
public class Customer : Entity 
{
        public string FirstName { get; set; }
        public string LastName { get; set; }
}

public class CustomerRepoTest
{
        public void Test()
        {
            var repo = new MongoRepository<Customer>();

            // adding new entity
            var newCustomer = new Customer {
                FirstName = "Steve",
                LastName = "Cornell"
            };

            repo.Add(newCustomer);

            // searching
            var result = repo.Where(c => c.FirstName == "Steve");

            // updating 
            newCustomer.LastName = "Castle";
            repo.Update(newCustomer);
        }
}