public void AddCourses()
        {
            foreach (var item in _allCourses)
            {
                if (item.IsSelected == true)
                {
                    CompletedCourseModel CompletedCourse = new CompletedCourseModel
                    {
                        StudentId = UserName,
                        CourseId  = item.CourseId
                    };

                    _sqlData.InsertCompletedCourse(CompletedCourse.StudentId, CompletedCourse.CourseId);
                }
                else if (item.IsSelected == false)
                {
                    CompletedCourseModel CompletedCourse = new CompletedCourseModel
                    {
                        StudentId = UserName,
                        CourseId  = item.CourseId
                    };

                    _sqlData.RemoveCompletedCourse(CompletedCourse.StudentId, CompletedCourse.CourseId);
                }
            }

            _eventAggregator.PublishOnUIThread("1");
        }