Android:

Step 1: Click the icon in the bottom-right corner of your screen.

Step 2: Click "Add page to"

Step 3: Click "Home screen"

Step 4: Click "Add"

Step 5: Click "Add" again

iPhone:

Step 1: Click the icon in the bottom-center of your screen.

Step 2: Click "Add to Home Screen"

Step 3: Click "Add"