hwo to give the variables in pdf template

Question

hello all,
 i my application i need to generate one form in pdf format which is filled by user for this i am see this form question and follow it but in this we give the form fields like variables ,when he submit the form we fill all the pdf template fields we can replace that template fields with our form values .... how can we set that variables in the pdf template ..... before see this one 
http://channel9.msdn.com/Forums/TechOff/117199-ASPNET-and-iTextSharp-free-PDF-Generator-for-NET

in this way only give reply i think it is the easiest way