asp.net - How to get JSON back from HTTP POST Request (to another domain) -

I am trying to use an API on a website, here is part of the manual:

Authenticated Sessions (taken from)

To create an authenticated session, you must request a authToken from the '/ authentication' API resource.

• URL: (This is not my domain)
• Method: Post
• Request format: Application / x- Www form- urlencoded
• Feedback format: application / xml, application / json
• Feedback code: 200 OK
• Response body:. Authenticated user details, including API version

• Additional data:. The "authToken" cookie and header containing the authentication token that should be used for incoming calls

  parameter: username / password

example < / H2>

request

accepting post / certification HTTP / 1.1: application / xml
content type: application / x-www form-urlencoded

users Name = my_username and password = my_password

Response

HTTP / 1.1 200 OK Set Cookies: authToken = 1KVARbypAjxLGViZ0Cg + UskZEHmqVkhx / PM ...;
authToken: 1KVARbypAjxLGViZ0Cg + UskZEHmqVkhx / PmEvzkPGp ... ==
Content-type: Application / xml; Charset = UTF-8

Question:

How do I work out this?

I tried jQuery, but it seems that there is a problem with XSS. The actual code snippet will be highly appreciated.

ps

I was looking at all the class C #

You enter Application / Jason in your Accept header, it tells the server that you want to respond to that format - not xml.