Once the app has downloaded, you can use the browser link, or manually enter the room extension found in the meeting invite. You should enter your name (as you would like it displayed in the call). You may also be required to enter a PIN number for the meeting, this PIN will be provided in the meeting email invite and it should be entered manually in the space provided.
When joining, the camera and microphone may be disabled. A line will be across these icons when they are disabled. To enable these, simply click on them.