What kind of world map are you referring to? There is no world map in GH2 because there is no 'world' there yet, only the vast emptiness of space.
If you begin in a spinner, find the spaceport and you can find a door there that will lead you to the spinner's exterior which is outer space near your spinner. if you travel to the edge, then you will find the space navigation map, but I don't recommend going there as you'll just be lost in space even more.
If you begin on an asteroid, If you exit the buildings, you'll find yourself on the asteriod surface. I believe you can launch yourself into space in the main building somewhere.
If you plan on transferring from one spinner to another, the only practical way of doing that is finding the travel agent at the spaceport and buy yourself a ticket. You'll be bringing along your currently assigned mecha with you. The other spare mecha you may have can be transported to wherever you are by the travel agent also, for a minimal fee.
