Teams (How to) Change an Existing Meeting to a Teams Meeting

Body

Office 365 Online:

Go to your calendar.
Click on the meeting that you wish to change.
In the pop up window click the Edit button.
In the bottom right click the More options button.
Next to the location information there is a toggle button titled Teams meeting.
Toggle the Teams meeting button on. (It is on if the bubble is to the right and shaded with your calendar color)
Press the Save button in the top left corner of your meeting window.
Your meeting is now set as Teams meeting, and participants will be able to join directly from their calendar.

Desktop App (Windows):

Go to your calendar.
Double click on the meeting that you wish to change.
In the toolbar at the top of the meeting window, press the Teams Meeting button.
Click the Send Update button.
Your meeting is now set as a Teams meeting, and participants will be able to join directly from their calendar.

Desktop App (Mac):

Go to your calendar.
Click on the meeting that you wish to change.
Click the two arrows in the top right corner of the pop up window to expand the meeting details.
In the toolbar at the top of the meeting window, press the Teams Meeting button.
Press the Send Update button.
Your meeting is now set as a Teams meeting, and participants will be able to join directly from their calendar.