I have recently managed to get the C&CN VASSAL module up and running (my first go at VASSSAL) and in general most things seem fine
When a leader is attached to a unit I cme across 2 problems.
First when trying to get the unit with the leader to take a hit, the usual right click does not offer that as one of the options when the leader is there. Obviously it should and I am doing something wrong .... But what?
Secondly, how do you actually detach the leader from the unit when you want to move him alone. The unit seems to keep getting dragged along with him.
If a Leader is attached to a unit, the menu options are not shown.
Therefore you should use (and learn and remember before) the menu options shortcuts.
The important shortcuts are also in the "Chart" window of the Vassal module.
To attach/spread a Leader from a unit, just doubleclick on the unit.
But my suggestion is, go online and play only one game with a familiar and experienced Vassal player.
So you would see and learn how the Vassal module is used (and the few differents to the live boardgame)
at least 10 time faster as you will do in 50 solo games