how can i take a pre designed house and put into my lot?

@cieberg     Hello!  For this example, I'll save the Base Game lot Streamlet Single in Willow Creek and then place it on the Oak Alcove lot in Newcrest. Here are the steps for saving to your Library and then placing the lot.

- In Build Mode, click the folder with the arrow icon to save the lot to your Library.

- Navigate to where you want to place the saved lot, click your chosen lot on the map and click the tool icon for building.

- When the chosen lot loads in Build mode, click on the Gallery button and when the Gallery window opens, click on the My Library tab.

- Locate the lot you saved and click on it. Then click on the Place Lot button.

- You will be prompted for whether or not you want to place the lot Furnished or Unfurnished. Then you'll get another prompt telling you that applying this will replace the current lot. After you make your selections, your saved lot will be built on the new lot that you've chosen. 

Hope this helps!