To become an Area Manager, use the edit map, position the map and set the zoom level to show the area you want to manage.
First make sure you are in the correct server:

https://www.waze.com/editor (if you are in USA/ CANADA)
https://world.waze.com/editor (Rest of the world)

Click on Permalink (located at the bottom of the screen on the right side):
(Click to Enlarge)

Then copy the address from the address bar in your browser:
Should look something like this:

https://www.waze.com/editor/?zoom=5&lat ... TFTTFTTTTT

https://world.waze.com/editor/?zoom=5&l ... TFTTFTTTTT


Fill out the form here and submit.

Link form: