Touch the desktop screen. Keep your finger on the screen for 2-3 seconds, then lift your finger off. There's your right click menu. There's "Personalize".

To right click a Start Screen tile, keep your finger on the screen for 2-3 seconds until the tile moves slightly, then drag the tile down a tiny bit and let go. There are the Unpin from Start, Uninstall, All apps & tile size right click options.