What's build mode ?

Build mode is where you can add or edit rooms. To get there go to the home store as if you were buying furniture. Then on the left hand side there should be two tabs, one for furniture, which you are probably on, and the one below that with a house on it. Click on that for build mode. But it says in your question that you want to build a garden. For that you need to go to the garden tab, which is on the right across from the furniture tab.

Hey! It's SyDMG here!

Alright, so here's how to get to build a garden. When you open build mode by clicking the chair with an arrow pointing upward. Then you see different "tabs". The different tabs are: furniture, house, outdoors, and inventory. Furniture is everything that you can put inside and sometimes and outside such as beds, showers, tables, chairs, and much, much more! In the house tab you can build and expand rooms and get stuff that goes on the walls of your house such as doors and windows. In the outdoors tab you can find stuff to go outside like gardens, plants and flowers (some plants go inside), and outdoor chairs. In the inventory tab you can see stuff you put in your inventory (by tapping on an object and then tapping the backpack icon).

Hope you enjoyed this short Sims tutorial by SyDMG!