Assuming you would like a step-by-step guide on how to queue songs on YouTube using an iPhone:
1. Open the YouTube app and sign in if necessary.
2. Find the video you want to play and tap on it.
3. Tap on the three dots in the top right corner of the video player screen. A menu will appear.
4. Tap Add to Queue. The song will be added to your queue and will start playing automatically after the current song finishes.