Your launcher isn't running. Go to
Google Play and install a launcher (many of us prefer
Nova Launcher). (Be careful that, when the choice comes up, it's installing to the right phone.) Then restart the phone and either Nova will come up, or the phone will ask you which launcher to use. Choose Nova and "just this time" (in case you don't like it). You should be able to get around in that. (Go to Nova Settings, in the app drawer, and you'll see that you can change just about everything in there - number of rows and columns, on the home screen and the app drawer, search bar or not, number of apps in the dock [the bottom row], number of docks, etc. You can even lock the screen, so you can't accidentally move things, and you can save the settings, so if you play around and mess up the look, you can restore them. [And the saved settings is in a file, so you can save as many settings as you have space for - hundreds.) Oh, also, most themes and icon sets work with Nova. If you like Nova, hit the Home button, then chose Always. (You can always get into Settings in the phone and change it later.)
