Mark Out Multiple Delivery Zones on Google Map and Store in Database
"Using Python and Django" only, you're not going to do this. Obviously you're going to need Javascript.
So you may as well dump Google Maps and use an open-source web mapping framework. OpenLayers has a well-defined Javascript API which will let you do exactly what you want. Examples in the OpenLayers docs show how.
You'll thank me later - specifically when Google come asking for a fee for their map tiles and you can't switch your Google Maps widget to OpenStreetMap or some other tile provider. This Actually Happens.
Background:
I'm trying to use a Google Map as an interface to mark out multiple polygons, that can be stored in a Postgres Database.
The Database will then be queried with a geocoded Longitude Latitude Point to determine which of the Drawn Polygons encompass the point.
Using Python and Django.
Question
How do I configure the Google Map to allow a user to click around and specify multiple polygon areas?