DataSource Controls :: How To Save Multiple Rows Using ADO.NET Entity Framework

public void saveOptionalCourses( ArrayList coursesAdded, int studentID)
{
StudentOptionalCoursesXRef XRefObject = new StudentOptionalCoursesXRef();
using (var EntityObject = new SchoolProjectEntities2())
{
foreach ( string list in coursesAdded)
{
XRefObject.StudentDetails = EntityObject.StudentDetails.Where(c => c.StudentID == studentID).First();
XRefObject.OptionalCourses = EntityObject.OptionalCourses.Where(c => c.OptionalCourseName == list).FirstOrDefault();
EntityObject.AddToStudentOptionalCoursesXRef(XRefObject);
}
EntityObject.SaveChanges();
}

with this above method and could save only last row that am returning remaining rows are iterated but are not saving on to database