Pip Boy local map tutorial help please

[PlankGas]

Help needed using the Pip Boy map in local mode, especially when inside multi level buildings please. How do I interpred the map ? How can I set a waypoint to follow a marker ? I've wasted countless hours getting lost, wandering in the same buidling(s) without sense of direction, up/down or where to go. Pip boy displays the goal but when I am standing on top of the marker there is nothing there, it must be on another level and I don't know how to get to.
No mods installed, plain vanilla game version. So far I couldn't find a Youtube video on how to use the map. Thank you.

[talgaby]

Local map is useless for most people, since it is closer to a sonar image flattened to a 2D pane.

Which marker you have issues with, what quest? Normally it just means you are on the wrong floor.

[PlankGas]

Curent quest: "Come Fly with me"
After countless hours of aimless wandering I found the quest goal (dead goal in basement). Now stumbling around to return to quest giver. I don't mind a 2D sonar map, as long as there is a route to follow.

[talgaby]

There usually is, no buildings are actual mazes, even if two locations will feel like it.
The Dead Money DLC though, that will be hell to you then, since it is a maze by design, constructed in a way that the objective pointer is perpetually useless for giving general directions, so it can teach you to navigate yourself.