Hi @sbasiima!
The step-by-step instruction explains this very well! \rightarrow Drone Tutorial
To make sure that no faces are missing you can use the Activate box assignment option shown in the top right corner. In that way you can make sure that you do not have to click every faces separately (which is a bit tricky in this case).
Let me know if you have any further questions. Good luck and all the best!
Jousef