Add items with same date to sub list of item main list - windows 8 store app c#

Add items with same date to sub list of item main list - windows 8 store
app c#

I have list of items in main list and main list has sub list and now I
need all items in main list where have same date add how items of sub
list. Does anyone know any recommendation? Here is sample:
https://dl.dropboxusercontent.com/u/40039421/Sn%C3%ADmka.PNG
public class calendarData
{
public string name { get; set; }
public string shortName { get; set; }
public DateTime HOURstartDT { get; set; }
}
public static List<List<calendarData>> getCalList()
{
List<calendarData> lessons = new List<calendarData>();
for (int i = 0; i <
test.getResp().GetStudies(0).LessonsList.Count; i++)
{
for (int j = 0; j <
test.getResp().GetStudies(0).GetLessons(i).HoursCount; j++)
{
lessons.Add(new calendarData
{
name = test.getResp().GetStudies(0).GetLessons(i).Name,
shortName =
test.getResp().GetStudies(0).GetLessons(i).Shortname,
HOURstartDT = new
DateTime(test.getResp().GetStudies(0).GetLessons(i).GetHours(j).StartTime.Year,
test.getResp().GetStudies(0).GetLessons(i).GetHours(j).StartTime.Month,
test.getResp().GetStudies(0).GetLessons(i).GetHours(j).StartTime.Day,
test.getResp().GetStudies(0).GetLessons(i).GetHours(j).StartTime.Hour,
test.getResp().GetStudies(0).GetLessons(i).GetHours(j).StartTime.Minute,
0),
});
}
}
List<List<calendarData>> listOfList=new List<List<calendarData>>();
foreach (calendarData subList in lessons)
{
listOfList.Add(new List<calendarData> {subList});
}
return listOfList;
}
Now I get result: List of 10 item and every items have list with one item.
How I can compare HOURstartDT and all items of first list which have same
date I need add to sublist of main list.
Example: Main list: item 1: name= "Jon", Date=14.6.2013 item
2:name="Steve", Date=15.6.2013, item 3:name="Michael", Date=14.6.2013
I need items with same date(14.6.2013) add to sub list like items and
remove these items from main list.