How to send request to server and get the response from server in ASP.NET?,

Hai guys ...

In asp.net web application, how can i send the data to remote server. and how can i get the server response from remote server using c#.
Suppose if iam passing username and password from the login form to server, how we can write the program to do this ,and same for the server response and it displays to browser.

I have heard abt this concept before this. that means, when client sends the data to server, the data should be converted into xml format before data transfer, and should be converted from xml to .cs orginal data after the server response. Then it will displays on the web browser. Am i right ????? If any changes there ,plz tell me ellaboratly.

i need the code also.

thanks and regards

Asok kumar