GOOD ON YOU for training your dog!!
I can not overemphasize how helpful using a clicker is, while training a dog. I resisted using one ("I'm doing fine without it, and i don't want to be chained to some gizmo" is what i said back then)
but wow, once i began to use a clicker, my dog "gets" tricks much much faster. Using clickers is how they train those killer whales at Seaworld, too.
We just CLICK/TREAT for correct moves, or attempts in right direction,
and silently ignore mistakes.
After the dog fully, solidly knows the trick,
then i fade out the clicker, and then, i fade out the treats, too. But i never fade the treats while i am still teaching him what to do.
For a spin, you could try luring your dog.
When dog is standing, move your hand which is holding a treat, so dog begins to turn.
CLICK/TREAT.
Over time, have dog, wait a lil longer, for dog to turn
even further, til you CLICK/TREAT.
over time, have your dog doing almost a full complete circle before you CLICK/TREAT.
THEN, over time, lure dog to do a full, complete circle before you CLICK/TREAT.
AFTER your dog is able to successfully complete a full circle, time after time, you can begin to fade the treat in your hand,
so that the dog is now following an empty hand.
Then add in your cue-word or hand signal, and begin to fade out the clicker, AFTER dog knows the trick very very well,
and then, begin to fade out the rewards to intermittant, treat/ praise/treat/praise/praise/treat/ and so on..
GOOD LUCK, let us know if that does not work, we can tweak it. and there are other ways to teach this same trick, if this way isn't working for you.