This is a general questions regarding building a website with user generated content. A new website will start with no content, then visitors to the site will not want to visit it again because there is no content for them to view.
For example, a review site like Yelp has no reviews will not have return visitors! How do you solve this?
You need to offer some reason to be there besides the reviews or whatever user-generated content you’re trying to integrate into the site. Yelp is a site that searches for restaurants and lists them by type and location, that is the main service which it provides. Offer the user-generated content as a secondary reason to come, then when the user-generated content starts to come in, slowly incorporate it more and more until it becomes the core of the site.
People will only visit your site if they get something out of it, even if it is something as simple as displaying their input in an interesting way.