To get New Town (sequal to LEGO City) you must collect enough gold bricks and build it's door in the Bonus Room (Door 6)
if you have just got it or have had it for a while, you'll of noticed that there's a boat that you can push into into the water. to drive the boat when you are on land, you must get a LARGE vehicle (i used a fire truck) and drive it into the water. now drive the truck towards the edge of the harbour. now get out and o in the boat, drive the boat towards the truck and it will start to float. keep driving towards land and you'll eventually land and be driving on the roads and the grass! :D