Get only checkbox checked id inside repeater

Question

I have checkbox inside a repeater . i want to get checkbox checked id only .. and then perform operation on checked checkbox clicked event in asp.net C#

<asp:Repeater ID="RepeaterNewEnquiry" runat="server" OnItemDataBound="RepeaterNewEnquiry_ItemDataBound"

OnItemCommand="RepeaterNewEnquiry_ItemCommand" OnPreRender="RepeaterNewEnquiry_PreRender">

   <ItemTemplate>

         <asp:CheckBox ID="ckbImportant" runat="server" CssClass="ckb"

            Style="width:100% !important;" />

   </ItemTemplate>

</asp:Repeater>