How do you go to other worlds in wizard101?

wizard city-

unlocked to everyone

grizzleheim-

getting to level 20

krokotopia-

save wizard city by defeating lord nightshade(quest also)

marleybone-

save krokotopia by defeating krokopatra in temple of storms(quest also)

mooshu-

save marleybone by defeating meowarity in the 20 floor Big Ben tower(quest also)

dragonspyre-

save mooshu by defeating the jade oni and you will talk to the headmaster and he tells you to talk to the myth teacher Cyrus drake(brother of malistaire drake) and he tells you to meet him in the myth tower and you defeat him(rank 7 myth 5000health) he guides you through dragonspyre to defeat malistaire drake and opening all the portals of dragonspyre(big story i know just answering a long question =D)

You also need a membership in order to even get that far. =D