Information when hovering over Marker on Map

[Moon_chilD 200]

Hey guys,
once again I chose a great title </sarcasm>.

What I'd like is, that I can add information about a Marker in a little box next to it once someone hovers with his mouse over the marker. 
The inspiration for this was "EasyTrack" by DasCleverle. The general idea can be seen here:

(Taken from this video: https://www.youtube.com/watch?v=kCTHJ0A1mN4&amp;t=364s)

While I could certainly reverse engineer this part out of EasyTrack I don't feel comfortable enough to work with "dialogs" and such. 
So I'd really appreciate if someone could help me with this.

Many greetings
Moony