To cast your phone screen on your TV you need to have Chromecast.
Follow the steps to successfully cast your screen-
Cast from Chromecast-enabled apps to your TV
Note: The Cast button isn't located in the same place on all Chromecast-enabled apps.
You can now cast videos, movies and TV shows directly to your TV.
To stop casting, tap the Cast button and then Disconnect.
You can also watch this step-by-step guide to do the same
You can check the complete specs of this phone: Samsung Galaxy J3
To insert Sim Card in Samsung Galaxy J3 follow these steps-
Taking screenshots using Samsung Galaxy J3 is as easy as it gets. Follow these steps to take a screenshot:
1. Open the screen you want to capture.
2. Press and Hold both the Power and Home buttons together for a couple of seconds.
3. You will hear a capture sound and animation on the screen. It means screenshot has been taken and saved in the gallery.
To know more visit this link-How to Take Screenshots on Samsung Galaxy J3