Using skills not on your skill bar

Okay, this is a total noob question and you all have permission to laugh, but this game has no manual so I will unashamedly ask away. I've rolled a Necromancer and just got "Summon Bone Horror". However this is my ninth skill and it doesn't appear on my skill bar. I've not been able to find a way to use the skill, swap it with another, or access it in any way -- and it's my necro's bread and butter. Please offer some tips, and thanks in advance.

Go into a town or an outpost. Hit the "K" button on your keyboard. Drag and drop the skills you want to change

Thanks, I keep forgetting that a lot of stuff can only be done in town. I had tried this, but obviously was in the wilderness at the time.

Yeah, I tend to find that a little irritating - esp. when your bar is full and someone gives you a quest, 50 feet from them, that you need to *use* those skills for. (Seriously - if you're just granting me skills outside of town, at least give me a chance to put them on the bar....)