Oh, @Katie_G, that is a big leap, and yeah, Sims 4 is quite different. The game launched with Willow Creek and Oasis Springs only. More worlds will probably be added as time goes by; for instance, there is a new one coming with the game pack this week. However, no you cannot create your own worlds or expand the existing ones at this time. Also, there is no ability to place lots; you have to work with the pre-existing lots. I know this feels limiting; sorry I can't give you better news. We do hope that this may change in the future, but no hint of it at the current time.