How could I get the response data from sending POST data using the WebBrowser control?

How could I get the response data from sending POST data using the
WebBrowser control?

Okay, so basically I am wanting to know how I can get the response data
after using the WebBrowser control's overload "Navigate" method. Here is
an example of what I am doing:

wb.Navigate("https://live.xbox.com/en-US/Friends/List", "",
Encoding.ASCII.GetBytes(post), "Content-Type:
application/x-www-form-urlencoded\r\n");
This is navigating my page to the first parameter but I have no idea how
to just get the response data from calling this. Also the result I want is
the response's body. Could somebody please help me. I tried using the
WebRequest and WebResponse ways, but they don't allow me to sign the user
into the Xbox Live website for some reason, resulting in myself not being
able to do anything and get 411 errors. I want to be able to do this with
the WebBrowser though. But if I can't, any help would be greatly
appreciated. Thanks guys.