After you've set up the package you can use the monitor:createartisan command to monitor a url. Here's how to add a monitor for https://laravel.com:
php artisan monitor:create https://laravel.com
You will be asked if the uptime check should look for a specific string on the response. This is handy if you know a few words that appear on the url you want to monitor. If you choose to specify a string and the string is not contained in the response when checking the url, the package will consider that uptime check failed.
If the url you want to monitor starts with https:// the package will also start monitoring the ssl certificate of your site.
You've just set up your first monitor. Congratulations! The package will now send you notifications when your monitor fails and when it is restored.