Default [Q] Windows 8 - set cookie


I'm writing an Windows 8 App which is parsing JSON data from an URL, which is working fine. I only have one problem: in every request to the URL I need to send a cookie with a specific value to "authenticate" to the external server. Otherwise I will not get the JSON data I'm requesting. I've been searching a lot on the internet but haven't found any solution yet which is working for Windows 8 Apps.

Can someone help me?

best regards