REgistration form

hi

I want to create a registration form in Silverlight, while I am filling that form it must be save in xml format. I have created a design page

        username:  om

      password:   prakash

                                 Login-> while clicking login in button a registration from will be load and I want to enter details of

name:om
age:25
address:india
location:Chennai

                  save

while I am clicking save--->>the above details must be save in xml format how can I dooo this

please reply