How-To: Place a House/Lot in-gameHow to Place Lots - Carl's Guide Photo Walk-through -
http://www.carls-sims-4-guide.com/help/place-lot.php
1. Load a saved game, and choose the town/world you want to place your lot in.
2. Go to the Gallery, and select the My Library tab.
3. Select the house/lot you want to place in-game. Make note of what size lot it is - this will be needed later.
-- Down in the right-hand corner of the popup there are two buttons. An arrow pointing at a square (this is called the Place Lot button) and a arrow pointing down and a pencil (this is called the Place and Edit button)
4. Click the Place Lot or Place and Edit button, your choice.
5. Pick a lot that's the same size or bigger, as the house/lot will place better. -- Click on it, then click on the check mark to confirm you want to place the house/lot there.
6. Choose to place the lot furnished or unfurnished.
-- If you pick unfurnished, you will not be able to choose furnished when you move a Sim in.
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Once the house is on the lot, click the hammer/wrench tool in the lower right-hand corner of the screen to go into build/buy mode. -Or- Move in a household from the library.