To add furniture select the "Furniture" button or use shortcut "F" key. Select from right hand panel the type of furniture that you'd like to add then click and drag the furniture into your space of choice.
You can also search for the furniture you’d like by typing your query into the search bar.
You can also filter furniture by space type or by selecting options from the drop down menu under the "Search Furniture" bar.
When selecting a specific piece of furniture in furniture mode you will be able to view the furniture details (i.e. quantity, name, and seat count) in the right hand panel.