1)Tap on Play Versus on the main menu of your application.
2) On the screen that just popped up, tap on Invite Friend
3)Choose the option that you and your friend prefer, and tap on it. You will be sending an invitation link via that channel and they can join the game by simply tapping on the link.
Please note that the game is not played live, and instead it's played turn by turn. So, when your friend taps on the link, they might not directly get into the game and they would be waiting for you to finish your turn first. Once you complete your turn, they will have access to the same questions, and once they finish their turn, you will be notified through the app.