"How do you make an app?"
The most difficult answer to explain to someone that knows nothing about code.

They usually think it's super easy!

"YOU don't."
Optionally add "At least not without spending a year learning to code and stuff" if they're someone you care about.

You tell the computer what to do for everything the app can do... No omissions.

Other people wrote already what to do on some scenarios you might want to implement and you can use that on you app! However you will have to learn about how that works in order to use it.