how one converts a private lightbox into a public one ? Btw, they do not say that a lightbox to be public should have 2 members
"The following is a list of your managed lightboxes. Lightboxes are a collection of related images. A public lightbox should serve the community and is available in the iStockphoto lightbox search after it contains at least 20 files. A private lightbox is used for personal and project related collections, and is accessible to anyone to whom a link has been sent."