I'll have to admit, beyond the 4th, I had no clue what the extra dimensions were supposed to be when it came to string theory. Let alone trying to imagine them was pointless. Well, here's a new book to do so and on its website contains a pretty slick tutorial on getting yourself up to speed. It's not so complicated as I had once thought. Granted you still really can't grasp its effects in its entirety, but you can at least get a handle on it now.

Imagining the Tenth Dimension