Most of the displays utilize an Army List such as the Stack List. The Stack List is an Army List of the units in a particular square. There are other Army Lists too, in a Player Information Window is an Army List of every unit in your army. When it comes time to do combat, the attackers and defenders are placed in Army Lists. Regardless of the Army List, they all share a few common traits assuming the list is under your control.
1) They are all scrollable lists showing the units Icon, it's current Strength (Morale) and Total Strength (Morale), and it's current move points.
2) Units can be selected by clicking on them. Multiple Units can be selected by holding the [shift] key down while selecting them.
3) Units can moved in the list by dragging them up or down in the list.
4)You can double-click a unit to bring up it's Army Information Window which tells you everything you need to know about a unit
5) Commands from the Commands menu are issued to units selected in the current Army List.
As far as Stack Lists go, you can always tell if you own a stack when you click on it in the Local Map. The top unit in the Stack List will be selected if you own those units
