Calculate first and last day of week, month, year

        Dim SelectedDate As Date = Today
        Dim FirstDayOfWeekDate As Date = SelectedDate.AddDays(SelectedDate.DayOfWeek * -1)
        Dim LastDayOfWeekDate As Date = FirstDayOfWeekDate.AddDays(6)
        Dim FirstDayOfMonthDate As Date = New Date(SelectedDate.Year, SelectedDate.Month, 1)
        Dim LastDayOfMonthDate As Date = New Date(SelectedDate.Year, SelectedDate.Month, Date.DaysInMonth(SelectedDate.Year, SelectedDate.Month))
        Dim FirstDayOfYearDate As Date = New Date(SelectedDate.Year, 1, 1)
        Dim LastDayOfYearDate As Date = New Date(SelectedDate.Year, 12, Date.DaysInMonth(SelectedDate.Year, 12))
        Dim DaysInTheYear As Integer = New Date(SelectedDate.Year, 12, Date.DaysInMonth(SelectedDate.Year, 12)).DayOfYear