Go to your Profile by clicking the drop down arrow on the right of the screen > Select 121 Meeting Set Up below your name on the left side > Enter your Calendly URL in the box provided > Click the red Save and preview button > Once this is complete you can then go to My Connections on the left of the screen > Click Manage my connections from the drop down > Then select the connection you wish to book a 121 meeting with. Both you & your connection must have Calendly set up or it will default to messaging.