To create a KML file, the best option is to use My Maps service provided by Google :

You need a valid google account to use it.

Log in to My maps service and create a new map

Once logged in, this the welcome page with, your existing maps:

To create a new map to be able to draw your zones, click on Create a new map

Draw your zones

You can change the name of the map, it's only for you, this will have no effect in the future KML generated file and importation step.

To draw a new zone/area, use the Add line or shape tool and draw your shape on the map. You need to draw a polygon aka a closed shape.

Name your drawn zones

The name of the created shape/area/zone is important there, it will be the name imported in Dispatch science. This zone name should contains only letters, numbers and underscores (ex: no white-spaces)

Export your zones to a KML file

Once you draw all your zones, you are ready to export the content to a KML file:

You could choose to export entire map or only a layer that contains zones.

Import a KML file to Dispatch Science

Once your file is downloaded on your computer, you can import it in Dispatch science Zones settings

Once the import is done, you should see in the zone list your imported zones with the same names as Google My Maps service. You are now ready to use your imported zones, congratulations !