If you are seeing a grey silhouette instead of yourself:
By Clicking on "Turn on Camera" below the assignment description you can easily fix the problem. Keep in mind that this may be an internet problem so if you start having problems hearing your partner, turn it off again, in that way the audio will improve.
If you are accidentally using your rear camera instead of the front camera:
On the address bar on the top, click on the video icon to the right side next to the star. Then click on Manage
Click on the camera label. Now click the first box and select the front camera option.
Close the settings tab and refresh the conversation page.