how to generate the barcode USING SOME FUNCTIONALITY

i HAVE ONE REQUIREMENT LIKE THIS PLZ TELL ME THE CODE HOW TO GENERETE QR CODE PLZ HELP ME ,i DON'T AN IDEA ABOUT GENERETE QR CODE USING ASP.NET
<html> <head runat="server"> <body>
COUPOUN TYPE:<asp:RadioButton ID="RadioButton1" runat="server" ForeColor="#006600" GroupName="coupon" Text="QR Code" /> Coupon value type:<asp:DropDownList ID="DropDownList1" runat="server" Height="24px" style="color: #0000FF; background-color: #66CCFF" Width="147px">                                     <asp:ListItem>Select type of value</asp:ListItem>     ...