OK, embarrassingly noob-ish question time. I'm a brand new player and am still figuring out the basics of the game, so I'm sure this is really obvious but what is the "power slot" and how do I equip it?

Specifically, I added the Amazing Follower Tweaks mod so my follower would ride a horse and the read-me tells me that I can load a Tweak Command in my power slot, only I'm not sure what that means. Thank you for taking pity on the noob.

Isn't this the C Key to cast a spell you have qued up? I have not rolled a magic caster per say, but the few spells I have used in the game I selected them then used the C key to cast them.

It's the same thing as shouts.

Are you sure you didn't accidentally load Oblivion?

I haven't used AFT in ages, but the power slot is Z (the same as shouts and racial powers). It could be a spell instead, though. Open the magic menu (P), find Tweak Command and click on it. If the arrow/marker/whatever next to it is empty, it's Z. If it works like a spell, then it will show L or R inside to indicate in which hand it's equipped.

Thank you everyone! Rosveen, that worked perfectly. Thanks for helping me figure that out.