To bad private albums are not supported by default but there are 2 options in which you can use them.
1 is a workaround and 1 is a code change.
Make you album public in picasa, load the gallery in rokin. Put the album on private in picasa.
You album will show in joomla because rokin is using the file links they are the same when a album is public or private.
The Code Change:
I made a change to the code that it can read private albums.
But there are requirements:
Zend Framework/Libraries must be installed on the server.
You must add the password of you gmail acount to after the username with a | in rokin like this: [user]|[password]
So when you are the only one that has access to admin console you can use this.
What my code change does it uses the zend libraries to connect to picasa.
I did not have time to make the passwordt hidden in some other way.
If the original maker of rokin (Alex Jonk) want the code please let me know, I'll send it to ya.