It is very simple. Open your Discord app, join a voice channel or a video call and simply tap the “Screen Share” icon from the control bar on your screen. Also, note that this feature is still rolling out and may not be available in your area. But if you do have access to screen share on mobile, a new dialog box will pop up with the message “Try it Out!”. Click on the button and then tap on “Start Now” and you should be able to share your screen now.