Age of Wonders 2 is a really old game, and as such a lot of details about the game mechanics are not explained in the tutorial of the game. If you jump into this game without reading the manual for the game, you will be pretty lost and get frustrated quickly.

You can find the manual here as (for whatever reason) it doesn't come with your purchased copy of the game:

http://aow2.heavengames.com/downloads/showfile.php?fileid=1083