To enable external CI for a repository, navigate to your user or organization’s settings page by clicking the user/organization icon in the navbar. From there, click the
BUILDS tab, then check the checkbox next to the repository of your choice.
Now, when you navigate to the builds page for that repository, any new builds will show a list of your GitHub-integrated build services, along with their respective statuses.
Note: For more detailed information on adding services to GitHub via their Marketplace, check out the GitHub Marketplace docs here.