The Start Meeting button on the home page (or under meetings on the Launchpad) allows you to start an instant meeting, or just share your screen with pretty much anyone.
What it does is put you on a call with an open conference bridge, which allows you to add multiple Biba contacts to the call, AND (or) non Biba users can call in using your dial in and PIN.
When you click Meeting, you are presented with two call options:
This immediately starts a call and opens up the call bridge so non Biba users can dial in using your PIN or a One Time PIN. It also pops up a pick list with your Biba contacts, so you can select as many contacts as you like and add them to the call. They will receive a new call alert on any device they're signed into Biba on.
Screen Share Only
This allows you to start a stand alone screenshare that can be viewed by a non Biba user on their browser, without being on a Biba call. Clicking it will immediately share your full screen, or you can choose to share a specific window from the More menu. The url to view your shared screen is at the bottom of the call roster, and clicking Copy will automatically copy it to the clipboard so you can easily send it.
You can start a call while doing the stand alone screenshare by clicking on Connect. This will open the call bridge so users can dial in, and your dial in and PIN info will be available to copy and send at the bottom of the roster, just like the screen share url. You can also add Biba contacts to the call by selecting Add Caller under the More menu.