1. To set up screen-casting, swipe down twice from the top of the screen to access the expanded quick settings. Tap the edit (pencil) icon and drag the Screen cast tile up from the hidden tiles.
2. To start screen-casting (mirroring), swipe down to open the quick settings and locate the newly added Screen cast tile. Tap it once and select the target device to cast to. Ensure that both devices are connected to the same local network.