Update database with LINQ to Entities

I've been doing some research on how to update an existing record using LINQ, but I'm not having any luck. This is the method I've created - intellisense does not like the db.SubmitChanges().

public void updateRestaurant(int RestID, int HoursID, string Web, string Desc)
{
    RestaurantsEntities db = new RestaurantsEntities();
    RESTAURANT restDetails = (from RESTAURANT in db.RESTAURANTs
                                    where RESTAURANT.REST_ID == RestID
                                    select RESTAURANT).Single();
    restDetails.HOURS_ID = HoursID;
    restDetails.REST_WEBSITE = Web;
    restDetails.REST_DESC = Desc;

    db.SubmitChanges();
}