Happy birthday. What's the easiest way to contribute data to it using my phone? I want to start mapping my city but I really have no idea how to do this. Any google maps style app that asks you questions about your surroundings?
https://wiki.openstreetmap.org/wiki/Every_Door
For more complete editing, I like to use "Go Map!!"
You need an OpenStreetMap-account, then long tap on the place, "actions", "Create POI" - enter the name and the type (restaurant, wastebin, whatever...) and save it.
If you're used to it and know the categories it takes maybe 30 seconds to do it everytime you visit a new restaurant or to add a new shop when you're waiting for the bus.