Other than teleporting to friends, you won't be able to get to Mooshu for a while, and there isn't anything for you to do there until you're given a Spiral Key to go there.
You have to complete each lower world's main (storyline) quests, in order to get a Spiral Key to the next world. The worlds are, in order from lowest to highest:
Wizard City Krokotopia Marleybone Mooshu Dragonspyre Celestia (still in development)
Grizzleheim is an optional world and doesn't need to be done.
Other than teleporting to friends, you won't be able to get to Mooshu for a while, and there isn't anything for you to do there until you're given a Spiral Key to go there.
You have to complete each lower world's main (storyline) quests, in order to get a Spiral Key to the next world. The worlds are, in order from lowest to highest:
Wizard City Krokotopia Marleybone Mooshu Dragonspyre Celestia (still in development)
Grizzleheim is an optional world and doesn't need to be done.