Dear Klaus -
I do not know your knowledge of aircraft flight instruments.
Let me try to explain in very simple terms...
In the middle of flight instruments, we have an "artificial horizon"
Oftentimes the top of display is blue (the sky), bottom is grey (earth).
A line separates the two (the "horizon")...
In the middle, there is a symbol representing the aircraft (the wings).
If the plane goes up, it is climbing, or turns (banks)...
In the "single cue" display, the "v bars" indicate which way to go...
Up, down, bank left, bank right.
All you have to do, is to match your airplane symbol into the "v bars"...
In the "double cue" display, the vertical bar gives a command left or right.
If the vertical bar goes to the left, bank the plane symbol to the left.
If you satisfy the command, the vertical line will go to center.
Same for the horizontal bar, bar goes down, put the airplane symbol down.
If the command is stisfied, the horizontal bar goes to the center.
Commands "satisfied" is the airplane symbol matching the V bars.
I sometimes say "fly formation in or with the V bars...
Or the needles in the center (for double cue displays)...
Perfect cross is in the center.
This display is used to fly i.e. an ILS approach.
Guidance for the localizer and the glide path.
I did not know how to explain to you, Klaus... hope this helps...
Happy contrails -