In the dashboard config file, you must add this configuration in the tiles key. The value belgian_trains should be an array of which each value is array with keys departure, destination and label
In app\Console\Kernel.php you should schedule the Spatie\BelgianTrainsTile\FetchBelgianTrainsCommand to run. You can let in run every minute if you want. You could also run is less frequently if you fast updates on the dashboard aren't that important for this tile.
// in app/console/Kernel.phpprotectedfunctionschedule(Schedule $schedule)
{
// ...$schedule->command(Spatie\BelgianTrainsTile\FetchBelgianTrainsCommand::class)->everyMinute();
}