The Favourites tray at the bottom of the Home screen gives you one-touch access to your most-used applications. You can customise these app shortcuts, except the centre one that opens your list of apps.
To change the app shortcuts:
Touch & hold one of the app shortcuts, then drag it up and drop it on Remove.
Swipe up from the bottom of the Home screen to open your app list.
Touch & hold the app you want. When the new shortcut appears, drag it to the empty spot in your tray.
Tipyou can also use folders in your Favourites tray.