How do I list an exchange?Manage Exchanges option which you can find under the People menubar option.
If you've signed up for an event, you will be able to do a mass addition of all other people who had signed up for the event. After returning from the event, log in and go to the listing for the event you attended. At the bottom of the signup list is a button that allows you to easily add other attendees from the event.
If you exchanged with just one person, you can add them as an exchange from their profile. Look for a button near the top-right side of their profile that reads, "Add as Exchange," and click it.