Windows form data-->web form-->windows form

Hi folks
I have windows form that ask the user to 'Add New customer' and the info entered by a user in this windows form will be First Name, Last name,
Address, City,State,Zip,DOB,Phone,SS,Driver’s License , Account Pswd. Now there is a URL on the windows form, upon clicking the URL i am stumped about the following two things
1- Upon clicking the URL , i want to log-in to the website, that opened on the URL click, automatically. I mean SOFTWARE should do the loging, rather than asking the user to enter user name and password by hand.
2-After signing in a webpage will open up that has same fields like windows form(the web page is also a Add New Customer page). I want this webpage to populate its fields with the data that we entered into the windows form?

Okay i have no idea how will i materialize aforementioned question number 1. Regarding the 2 , there are folks who have suggested me followign two things
i)-windows form data should be taken to the web form in a query string(i don't like this approach)
ii)-The data entered in a windows form should be stored into a database/file(preferrably in XML format), and then webpage should read the data from this file/database(I like this , however i don't know if its gud or not...i mean there could be better solutions)

So please guide me....and enlighten me with the probable solutions. I really appreciate your time and effort. Any help, comments will be highly appreciated.
Regards
Ahmed Saran