The camera activation button is located in the upper left of the meeting client represented by a camera icon with a slash through it (assuming that your camera is not on).
Clicking this icon will display a prompt. Here you will have to allow access to your camera and microphone by clicking on the green 'allow' button. At this point you will be presented with a display that allows you to choose the camera and microphone that you would like to use.
After the camera and microphone have been chosen for the esession, you may set yourself 'live' on the stage by clicking the 'Go LIVE' switch.
Note: newrow_ automatically recognizes your computer's default devices upon selecting the activation button.