Locate the experiments to import in your file manager app.
Notice that the experiments might be "hidden" in the internal storage folders.
Once located, click and hold the experiment file to access the actions, or on the 3-dot button at the right of the file to access it's actions. You will see actions like
Share > Arduino SJ,
Open with > Arduino SJ, or similar.
Done! You are all set and can continue experimenting.