Try This
<h2>Calendar Control Example</h2>
<asp:calendar id="Calendar1" runat="server" forecolor="Orange" xmlns:asp="#unknown">
BackColor="Gray" ondayrender="Calendar1_DayRender"
onselectionchanged="Calendar1_SelectionChanged"></asp:calendar>
<br />
<asp:label id="DatesLabel" runat="server" xmlns:asp="#unknown"></asp:label>
protected void Calendar1_SelectionChanged(object sender, EventArgs e)
{
DatesLabel.Text = "You selected these dates : <br />";
foreach (DateTime dt in Calendar1.SelectedDates)
{
DatesLabel.Text += dt.ToLongDateString() + "<br />";
}
}
protected void Calendar1_DayRender(object sender, DayRenderEventArgs e)
{
if (e.Day.IsWeekend)
{
e.Cell.BackColor = System.Drawing.Color.Green;
e.Cell.ForeColor = System.Drawing.Color.Yellow;
e.Day.IsSelectable = false;
}
}