Interactive documentation

For some reason I can never find where I need to go to enable Travis on a repository. It would be nice if you could create an interactive help mechanism ( preferably on Travis front page ) where I could copy/paste the repository URL to get instructions on what to do to enable Travis for that repository. I think the process is different depending on some parameters. Maybe it depends on if the repository is public/private or new/old. All I know is I have done it approximately ten times and I still have no idea how it works.