How to Put an Android App in the Favorites Tray
The line of icons at the bottom of the Android Home screen is called the favorites tray. It includes the Apps icon, as well as other icons you place there, such as the Phone or Dialer app icon, or any app you use most often. The favorites tray icons appear the same no matter which Home screen page is displayed.
Icons are managed on the favorites tray in one of two ways:
Drag an icon off the favorites tray, either to the Home screen or to the Remove or Delete icon. That action makes room for a new icon to be placed in the favorites tray.
Drag an icon from the Home screen to the favorites tray, in which case any existing icon swaps places with the icon already there.
Of these two methods, the second one may not work on all phones. In fact, the second method may create an app folder in the favorites tray, which is probably not what you want.