Once you have installed See and started the app.
You will be presented with a screen that allows you to Invite Friends. When you tap this button you will be presented with a list of apps that you can use to share your special See invite link. You can share this link with your favorite app - Messenger, WhatsApp, SMS, Email, Slack or whatever other apps you have set up.
When you press Start you will start your video conferencing experience. Anyone tapping your link will also be joined. You or your friends can start a screen share by tapping the icon in the bottom left to start sharing their screen. Everything on your screen will be now share even when you exit the See app.
To end screen sharing, return to the app and press the screen sharing icon again or end the call.