Welcome to Android Central! The launcher is the piece of software that controls what your homescreen looks like and how it works. If you're using your phone normally to open apps, you're using the launcher. Are you asking how to install an alternative launcher like Nova? Or do you want to look at all of your apps? Open the App Drawer by tapping its icon--it usually looks like a grid of dots in a circle, located in the Favorites Tray at the bottom of the homescreen.