<asp:Repeater ID="rMenu" runat="server" OnItemCommand="rMenu_ItemCommand">
        <ItemTemplate>
        <asp:Button runat="server" ID="itemMenu" CommandName="Select" CommandArgument='<%#DataBinder.Eval(Container.DataItem, "id")%>' >
        </asp:Button>
        </ItemTemplate>
        </asp:Repeater>

protected void rMenu_ItemCommand(object source, RepeaterCommandEventArgs e)
    {
        switch (e.CommandName)
        {
            case "Select":
                LoadContent(Convert.ToInt32(e.CommandArgument));
                break;
        }

    }