How to make an editable map on the site?

Question

OpenStreetMap

Where to look for information, what to look for?
How to make a web page with a map.
The map is made up of layers. The city map itself is loaded onto the lower layer (from OpenStreetMap), the upper layers are loaded from the database. And it is also necessary that the user can enter elements (point / line / polygon) on the desired layer with the mouse and they are saved in the database.

Answer 1

You need to put a click handler on the map. And send XMLHttpRequest to the server

Answer 2

So far, I realized that to solve my question, you need to look towards Leaflet and GeoJSON.
Now I would like to understand how to load layers from the database onto the map. And how to edit these layers from the site.