If your model look something like:

using System; 
using System.Data.Entity; 
using System.ComponentModel.DataAnnotations; 
using System.Data.Entity.Infrastructure;

namespace MvcApplication3.Models
    public class MyTable
        public int MyNum { get; set; }
        public string Name { get; set; }

    public class MyTableDBContext : DbContext
        public DbSet MyTable { get; set; }

Then, your connection string in Web.config must look like:

 <add name="MyTableDBContext" connectionString="Data Source=MyPC;
													Initial Catalog=MyDb;
													Integrated Security=False;
													Persist Security Info=True;
													User ID=myUser;
		 providerName="System.Data.SqlClient" />

Note that MyTableDBContext is in connection string and defined as DbContext in the model, and Integrated Security is false (true means to Windows Authentication)