I live in Canada, but my servers are hosted by a third party in the United States. My website is a sports forum type of site where user's provide almost all of the content. I have a concern now if a user posts some bad content will I be liable? For instance, if a user/bot posts some content in the form of threats, illegal pornography, false claims about companies, copyrighted information, etc am I liable for this information? In essence, can I get into legal trouble for this content on my site. On my site I have a "report bad content" feature in which user's can report bad content and I can review, but obviously I can't go through all the content myself everyday in real-time to make sure. I was thinking of a site like Facebook where a user can write anything, how does Facebook stay clear of liability for user content?

Side not: I am a programmer and have little legal knowledge.