How to save an object that contains a collection of other objects using Entity?

Question

Entity Framework

public class Position
    {
}

Answer 1

public class Position
{
 public string ConsumptionRateUnit { get; set; }
public List<Operation> Operations { get; set; }
}
public class Operation
{
public int? Id_position { get; set; } 
public int? Id { get; set; }
public string FormValuation { get; set; }
}
var items = (from position in doc.Element("TechNorm").Elements("Position")
                             select new Position()
                             {
                              ...
                             }
using (var db = new LoadNsiContext())
                {
                    foreach (var operation in items)
                    {
                        db.Operations.Add(operation);
                    }
                    db.SaveChanges();
                }

There was an error cannot convert element type to iterator type in foreach (var operation in items)
How to save an object that contains a collection of other objects using Entity?