Yes, of course outside the theme context the functions are not available. See the user guide on "zenphoto as a plugin". There is also a tutorial for the object model (of course dependent on the theme context as well).
i have followed the user guide but i cant figure it out,
can you maybe write the code for me?
i know im on the right track but i'm struggeling with this problem for 2 days now and i cant figure it out.