To select all week days when week number in MonthCalendarAdv is clicked handle ItemClick event and use following code:

C#

private void monthCalendarAdv1_ItemClick(object sender, EventArgs e)
{
    DayLabel label = sender as DayLabel;
 
    // If day label is clicked and label is used to display week of year
 
    if (label != null && label.IsWeekOfYear)
    {
        // Ensure that multi-selection is enabled
 
        monthCalendarAdv1.MultiSelect = true;
 
        // Get the month control that represents the month that label is assigned to
        // so complete date can be retrieved
 
        SingleMonthCalendar month = label.Parent as SingleMonthCalendar;
 
        // Parse the week of year from text
 
        int week = int.Parse(label.Text);
 
        // Get the month where week of year clicked resides
 
        DateTime d = month.DisplayMonth;
 
        // Forward date to the beginning of the week
 
        while (CultureInfo.CurrentCulture.Calendar.GetWeekOfYear(d, month.WeekOfYearRule, month.FirstDayOfWeek) != week)
            d = d.AddDays(1);
 
        // Finally select the week...
 
        monthCalendarAdv1.SelectionStart = d;
        monthCalendarAdv1.SelectionEnd = d.AddDays(6);
    }
}

VB

Private Sub monthCalendarAdv1_ItemClick(sender As Object, e As EventArgs)
    Dim label As DayLabel = TryCast(sender, DayLabel)
 
    ' If day label is clicked and label is used to display week of year
 
    If label IsNot Nothing AndAlso label.IsWeekOfYear Then
        ' Ensure that multi-selection is enabled
 
        monthCalendarAdv1.MultiSelect = True
 
        ' Get the month control that represents the month that label is assigned to
        ' so complete date can be retrieved
 
        Dim month As SingleMonthCalendar = TryCast(label.Parent, SingleMonthCalendar)
 
        ' Parse the week of year from text
 
        Dim week As Integer = Integer.Parse(label.Text)
 
        ' Get the month where week of year clicked resides
 
        Dim d As DateTime = month.DisplayMonth
 
        ' Forward date to the beginning of the week
 
        While CultureInfo.CurrentCulture.Calendar.GetWeekOfYear(d, month.WeekOfYearRule, month.FirstDayOfWeek) <> week
            d = d.AddDays(1)
        End While
 
        ' Finally select the week...
 
        monthCalendarAdv1.SelectionStart = d
        monthCalendarAdv1.SelectionEnd = d.AddDays(6)
    End If
End Sub