DateTime And Day

private List<DateTime> GetDates(DayOfWeek dayOfWeek, int month, int year)
{
   List<DateTime> dates = new List<DateTime>();
   int totalDaysCount = DateTime.DaysInMonth(year,month);
   int dayCount = 0;
   do
   {
       DateTime currentDate = new DateTime(year, month, ++dayCount);
       if (currentDate.DayOfWeek == dayOfWeek)
           dates.Add(currentDate);
   } while (totalDaysCount > dayCount);

   return dates;
}

Public Function GetDates(ByVal dayOfWeek As DayOfWeek, ByVal month As Integer, ByVal year As Integer) As List(Of DateTime)
        Dim dates As New List(Of DateTime)
        Dim totalDaysCount As Integer = DateTime.DaysInMonth(year, month)
        Dim dayCount As Integer = 0
        Do While (totalDaysCount > dayCount)
            dayCount += 1
            Dim currentDate As New DateTime(year, month, dayCount)
            If (currentDate.DayOfWeek = dayOfWeek) Then
                dates.Add(currentDate)
            End If
        Loop

        Return dates
    End Function

List<DateTime> dates = GetDates(DayOfWeek.Sunday, 1, 2011);

List<DateTime> dates = GetDates(DayOfWeek.Saturday, 4, 2011);

List<DateTime> dates = GetDates(DayOfWeek.Friday, 11, 2009);