How do you choose which skill to assign to it? :rolleyes:
Usually, to set certain parameters for an object, you need to select it on the map and press Object Properties (the 11th button from the left) or the Spacebar key. But this can only be done with certain objects, not all of them. For example, you can do it with a Ruined Mine or a Garrison, but not with a Witch Hut. :)