1. To share your screen or a PowerPoint presentation, please have the content open before you begin the meeting. 

  2. Select the Share button.

  3. You can select the individual application or the option to share your entire screen. [Note that if recording and sharing a powerpoint or document, you will need to keep the powerpoint or document up on your screen as your primary window for it to appear in the recording.]

Sharing video is slightly different.  For information on sharing video, see this article here.