Either create a new meeting or open an existing one. Click Add Online Meeting in the Ribbon and all of the connection information will be automatically added to the message body. The first time you do this, you will be required to sign in.
Return to the meeting in Outlook to start the Online Meeting (a start button will appear to the right of the message body).
Don’t forget that you can create a custom meeting URL by going to the Online Meeting tab inside of Elevate. However, links in your calendar meetings will not be automatically updated if you change this.