Media space

The media space, or main stage, in Collaborate is where the content of the session is displayed. The size of this space is maximized to create an inherent full-screen experience at any screen size.
Select the picture-in-picture window to switch your focus. Your main screen becomes the picture-in-picture and the picture-in-picture becomes the main screen.
If there is no shared content, you’ll see attendee profiles and video in a grid view. You can switch between a grid view and a view that follows the speaker.
With the follow-the-speaker view, the focus moves to the current speaker as the discussion unfolds.
The Ultra experience switches to follow-the-speaker view automatically when there are more than five attendees.

Grid view

Follow the speaker view
Media space tools
Tools that appear in the media space relate directly to what is happening in the session at that moment. Tools also depend on the permissions moderators set.
Tool Description
Audio
 Turn your audio on. Lines through the microphone icon means that it is turned off. Select Share Audio to turn it on.

With your keyboard, press Alt + M to turn your microphone on and off.
Video
Turn your video on. Lines through the camera icon means that it is turned off. Select Share Video to turn it on.

With your keyboard, press Alt + C to turn your camera on and off.
Hand raise
Raise your hand to answer a question or get another moderator's attention. Select Raise Hand.

With your keyboard, press Alt + H.
Collaborate panel
Open the Collaborate panel.
Session menu
Open the Session menu.
Follow the speaker view
Switch to the follow-the-speaker view.
Grid view
Switch to the grid view.
Picture-in-picture
Change the focus of your screen. If shared content is on your main screen, switch to watching the speaker. Select the picture-in-picture to bring that content to your main screen.
Status
Show your status as away. Point to the green checkmark by your avatar image and select Set as Away. Select I'm back! when you return.

You can also update your status to give feedback during the session.
Session menu

The Session menu opens a collection of high level session actions and information. Open it using the Session menu button at the top left of the screen.
Session menu tools
Tools and features you use only once or twice during a session are conveniently grouped here.
Tool Description
Start a recording
 Moderators can start recording the session from the Session menu.
Use your phone
Get a dial-in number and unique PIN to use your phone for audio during a session.
Report an issue
Report an issue with the session.
Help
Go to Blackboard Collaborate help on help.blackboard.com.
Learn how to use Collaborate
Open tutorials on how to use Collaborate.
Leave session
Exit the session and complete a quick survey to tell us about your experience.
Close
Close the Session menu.
Collaborate panel

The Collaborate panel takes your session experience to the next level. You now have a single space to go to engage other attendees with all the great collaborate tools
Collaborate panel tools
Tool Description
Chat
 Chat with everyone in the session. Open the Collaborate panel and select Open Chat.

The moderator can turn chat off.

The emoji pack for Collaborate with the Ultra experience supports diversified emojis and Unicode 8 characters.

Use one of five supported skin tones on any human emoji. Add underscore, tone, and the supported tone number (1 through 5) to your emoji when typing. Don't forget the colons on either end of your emoji text.

Example: :wave_tone5:

Collaborate's chat history only has 50 messages displayed at any given time.
Attendees panel
View the list of attendees. Open the Collaborate panel and Select Open Attendees List.
Share Content
Moderators and presenters can share a blank whiteboard, an application, PDFs, PowerPoint® presentations, and images in GIF, JPEG and PNG formats.
My Settings
Add a profile image, set up your audio and video and your notifications. Open the Collaborate panel and select My Settings.
Close
Close the Collaborate panel.
Share Whiteboard
Moderators and presenters can share a blank whiteboard from the Share Content panel.
Share application
Moderators and presenters can share their entire desktop or a single open application from the Share Content panel.
Share files
Moderators and presenters can share PDFs, PowerPoint® presentations, and images in GIF, JPEG and PNG formats.
Polling
Moderators can start and run polls during a session.
Breakout groups
Moderators can start and run breakout groups.
Timer
Moderators can start timers.
Options
Open the attendee options menu.
Collaborate panel with a screen reader
Using the "button" or link quick keys (B in JAWS or VO + Command + L in VoiceOver) look for the button labeled "Open Collaborate Panel".
If the link quick key in VoiceOver doesn't identify this action, try VO + Command + G to go to the next graphic, or VO + Right Arrow to read the next item until you find it. 
Activating this button opens a 'tab list' which works as follows:
The first tab "Chat" is focused by default. Use the TAB key on your keyboard to interact with the elements within the chat panel including reading and posting messages.
Use the right and left arrow keys to move through the tabs (Chat, Attendees, Content, and Settings).
Once a tab has focus you can use the TAB key to move through the elements on the page. Or back to the list of tabs.
Tab to the "close Collaborate Panel" button to exit out of this experience.
Chat history keyboard controls
Use the keyboard controls at the top of the Chat panel to move between messages. The keyboard controls are only available after messages have been posted in Chat and are only available with keyboard navigation.
From the text entry field in the Chat panel press Shift + Tab to open the keyboard controls. Or from the Chat with menu at the top of the panel press Tab.
By default, the focus is on the Next chat message control. Press Shift + Tab to find the Previous chat message and First chat message controls. Press Tab to find the Last chat message control. Collaborate's chat history only has 50 messages displayed at any given time.
Press Space Bar to activate the control and listen to the message.
Press Tab to move through the controls and return to the chat text entry field.


Source: Blackboard Collaborate Ultra