The easist way to trade ATCs is in person.
But it can be hard to find an ATC group.
So there are two other options:
Facebook Trading Groups and Online Swapping Groups.
Join the group.
Post a card and wait to see if someone requests a trade.
OR
Post a comment on a card that you want to acquire, then send a message via Messenger to that person.
In "Emily's group," there is an entire section of helpful hints. It is silly for me to repeat all of these. See THIS PAGE. Be sure to scroll down and read everything!
How to Join a "Swap"
coming soon