Where to paste the google_auth code and which information should go into the areas?

Hello,

This wonderful module seems to be exactly what I was looking for so I really hope I will get this up & running.
I'd like to use this module for all my registered users - in the issue queue I've read that this is possible - I hope this info is still correct?

Now I have some questions and your help would be absolutely appreciated.
I installed google_auth 6.x-1.0 and the latest Picasa 6.x-dev module, registered for Google AJAX Feed API key and pasted the key into the key field on the Picasa settings page.
Ok, and when I try to create a Picasa album or photo I get the error: "Parameter "scope" is not correct or does not exist."
I know that I have to paste the code from the google_auth modules project page... but I really don't know where I have to put this snippet in.

function picasa_dostuff() {
  // Require the user to be authenticated with google
  google_auth_required('http://picasaweb.google.com/data/');

  /* do stuff that required the user to be authenticated */
}

I also don't know what information should go into the section where the link "http://picasaweb.google.com/data/" and the comment "do stuff that requiered the user to be authenticated" is written.
It would be amazing if you could help me with this.

The other thing is: currently I'm working on a subdomain. AFAIK it should also work but I wanted to let you know this... maybe it could also be important for some reason.

Thank you very much for your work!

Best regards,
Stefan