It is a bit different if depending on what device you are using. Take note AirDrop has to be turned on for both users for this sharing feature to work.
- Mac: "right click" on the item you wish to share, select Share, then select AirDrop, and select the person you wish to send the item to. Or you can open the AirDrop screen and drag the document to the person you wish to share it with.
- iPad/iPhone: open the menu for the item you wish to share, scroll until you see Open in Another App, then select AirDrop