On DeadSimpleScreenSharing.com click on the "Share your Screen" Button to start the screen share
In the next screen you will be provided a join meeting code. Give this code to your participants and they can go to this URL / website join the meetings
Share the meeting code with other for them to join the meeting and share your mic, camera and screen with them.
To Join an existing meeting simple go to the URL / Website which the meeting organizer or admin gave you.
When you go to the URL the browser will ask you for access to camera and microphone, if you give the access then you can share your camera and microphone with other participants in the meeting