Re: how do i create a new world
that depends on what you mean if you mean start a game in a world that comes with an expansion and or store world just go to the main menu +new game select a world from there and launch then move your sims in from the library if you saved a copy of them or create new sims to start playing OR i think one of the patches introduced a can move to any world option (not 100% sure if a expansion is needed for it though) but in anyways have a sim use a phone or pc and use the travel/real estate option and you can move to new town that you have in your list
on the other hnd if you mean create your own playable worlds you need to download and install CAW http://www.thesims3.com/game/tools/world
http://www.thesims3.com/content/global/downloads/caw/help_en.pdf
http://www.thesims3.com/content/global/downloads/caw/CaW_WalkThrough.pdf