help with passing querystring

 have designed a drop down --ddlyr(lists the yrs.from 1986 to 2008)
 Radio  button "rbContract" and a submit button
I need to pass query from main.asp to "contractsummary.asp" if user select (a year between 1986 to 2000 AND radio option Contract) .
How I can wite C# code in main.cs
Pl. help.....
 
Here's my main.Asp file look like:--
 
<asp:Content ID="Content1" ContentPlaceHolderID="ContentPlaceHolder1" runat="server">
    <div style="height: 283px">
   
    <table  cellspacing="10" border=".02">
    <tr >       
      <td align="left" width=250>
        <h2 >Fiscal Year  </h2>
&nbs ...