pass the value of a textbox to another page and access the value from there

I've to pass the value of a textbox to another page using OnClientClick event. I need to show the page in pop up window with CenterWindow.
<asp:Content ID="wrapperContent" ContentPlaceHolderID="wrapperContentHolder" runat="Server"> <table> <tr> <td> Area Name </td> <td> <telerik:RadTextBox ID="areaCode" runat="server"></telerik:RadTextBox> <telerik:RadButton ID="search" Text="Search" runat="server" SkinID="search" OnClientClick=""> </telerik:RadButton> </td> </tr> </table> </asp:Content> OnClientClick the pop up window should open the page "willis_searchAreaName.aspx" with the value of "areaCode". The popup window should display in the centre of the screen. How can ...