In case someone finds useful:
Uri uri = new Uri("http://localhost:50222/odata");
var container = new CourseServiceRef.Container(uri);
CourseServiceRef.NotNeeded newTempAccount = new CourseServiceRef.NotNeeded()
{
Email = model.UserName,
Username1 = model.UserName
};
if (newTempAccount != null)
{
container.AddToNotNeededs(newTempAccount);
container.SaveChanges();
}