https://www.instructables.com/Re-Felt-Your-Shed-Roof/
The roofing felt is meant to be put down first and then covered with a layer of shingles or rolled roofing as the felt will not hold up to the weather on its ...

https://www.youtube.com/watch?v=balrjtY5a7I
Fix it with Fowler will show you how to felt a shed roof and ensure it lasts a long time using some basic Do It Yourself tools.

https://www.youtube.com/watch?v=DTg3iEZ0g94
I always recommend sticking the roof felt down with bitumen under the whole sheet to stop any wind getting underneath. Loads of sheds get ...