Authentication and integration

Hello,

I'm trying to integrate CKFinder within my website, but when I try to access it it tells me that uploading files is impossible and that the administrator should be contacted. I read that I need to use the CheckAuthentication function, but I don't know exactly how to use it. We already have an user authentication script on the website.

So how can I make the CKFinder work with this function?
Thanks in advance