how do i get the random gallery module on my front page to show thumbnail previews of gallery photos, but when they click on it, they have to register to see the photo?
Thats a setting inside the gallery not file specific. Under registration options in photopost admin set the option users need to be registered to view images to YES.
That would depend on your site right. Our software they register with photopost or your forum depending on your setup. The option I noted tells them to register and stops them from viewing the actual photo.