How do you explore the worlds of the spiral in wizard101?

I think, will unlock them as you move along in the game.

Well also you have to be a level 13 to enter the spiral and have finished the main 3 streets talk to Merle, he will give you a quest to defeat lord nightshade, then talk to him. You will talk to Bartleby in Ravenwood. The Spiral Door is inside Bartleby.