Hi, Welcome to the Forum pretorian !
Here are all important links:
http://lmms.io/forum/viewtopic.php?f=1&t=4740
-A few rules and useful forum instructions
Can anyone of you recommend any good introduction to read notation?
I think this one is great:
https://www.musicnotes.com/now/tips/how ... eet-music/
Can you maybe also recommend efficient ways to put notation into lmms piano roll?
...Autch
No. :| There is no way at all to add any kind of symbol or color at all in piano-roll. Not even in sing-editor, except for coloured beat-tracks, without notes.
LMMS has yet not focused on this aspect of music, so in that direction, LMMS has nothing.
Best i can think of is to take screenshots of piano-roll, draw on those in any paint program, and then keep the drawings in folders with the project, and use them as references