Callback_url JFacebook

[Mind gem]

Hello,

Not sure if this is the right place, but here goes:

I'm working on a Facebook module which eventually should retrieve group information of one group (group description, picture and such).

I'm trying to incorporate the following:

https://github.com/joomla/joomla-developer-docs/blob/master/docs/en/cms/platform/facebook.md

The problem I have is the variable callback_url.

The description says: "which is the script's path"

What should i use here for my module? I get to the point:

$oauth->setToken($token);
$access_token = $oauth->authenticate();

But this now adds ?code={token}  to the url of my site

When I hit refresh on it I get a Facebook error that the token has been used.

Something like this "$user = $facebook->user->getFeed($user_id);" has to be commented out stil in my script because it gives me an error also.

I'm not emotionally attached to my trial and error thingy, so if there is someone who knows an out of the box Joomla integration of JFacebook to get basic group information (or user information I then can convert) would also be appreciated.