That was very likely Street Complete which is self explanatory and a great way to start. You are adding all kinds of useful information about any kind of object or building with this.
There’s also Vespucci which allows to alter the whole map (ie edit streets, POIs and so on) but takes a lot more to get familiar with.
Maybe the wiki from r/WhatsThisSong is useful for you, they describe first steps to identify songs: https://old.reddit.com/r/WhatsThisSong/wiki/index/
Also humming it for others to get an idea can be useful too.