dropdownlist selected item in checkedlist box

hi

in my web app i am taken one dropdownlist, button and chekboxList controls. and in dropdownlist items are Red, Blue, Green.

and in checkedlistbox i take items are

<asp:CheckBoxList ID="CheckBoxList1" runat="Server">
        <asp:ListItem Text="Red" Value="red"></asp:ListItem>
        <asp:ListItem Text="Blue" Value="blue"></asp:ListItem>
        <asp:ListItem Text="Green" Value="green"></asp:ListItem>
    </asp:CheckBoxList>

my aim is when i am selecting Red item in dropdownlist and i click button that time Red checkbox is selected. similarly to all

please give me a solution and please give a some sample code todo this.

Thanks