If you do not have the Blackboard Launcher or you are not prompted to download it, download it here:.If it prompts you to download the launcher, depending on your browser, it will download a file that looks like this (I'm currently using Google Chrome for this screenshot).When you Join a Bb Collaborate session, it should prompt you to download the launcher (if you already have it, it will simply launch a 'llab' file, and see step 9).
How to run the Bb Collaborate launcher for Mac OS X 10.8.4 or later
