Things are added to the canvas (the area where you create and edit flows), from your library.
Your library is simply a collection of your things. It may contain things that have been pre-populated for you, or that you have added from the Stringify marketplace.
To add one or more things to the canvas, tap on the + button at the bottom of the canvas.
Image: Add Button
This will bring you your library. Tap on one or more things (a green checkbox will appear on top of each selected thing), and when finished, tap on the Add button.
The things you just selected will be shown in the staging area of the canvas. The staging area is simply a temporary holding area for your things as they wait to be dragged onto the canvas.
Drag and drop the things from the staging area to an open spot on the canvas. If needed, the thing will "snap" into the closest open spot.
Image: Staging Area
Repeat as needed to add things to the canvas.
Tip: Missing something from your library? From the Dashboard, tap on Discover, to go to the Stringify marketplace. From there you can find and add numerous additional things to make even more incredible flows.