If your camera and mic is working correctly with WebRTC, you will see and hear yourself here: https://apprtc.appspot.com (Click join)
If you have an issue, check if the camera or mic works on a different browser and a different application like Skype. For instance, if you are using Firefox check if it works with Chrome instead.
Make sure that you're clicking allow within the browser as well.
Note: Not all attendees will have mic or camera access. It is up to the host to enable access.