Paislia. I think people are mixing up the rules for the swap thread and the TC thread.
The instructions for each is the first post in the threads
For the swap
Rule #3 states
No chit chat in this thread. If you want to trade with someone after they've posted items or if you have questions about those items, SEND A PM. Literally, post a trade, edit your post once it's done...that's it. Seriously. That's it.
That means you pm the poster with your offer of a trade. Then when they accept one they come back and edit their post to say it has been traded.
In the TC thread
You must post your want for a posted offer IN THE THREAD (no PM's) along with the date of your last taken TC offer.
Then AFTER the poster says its yours they
MUST edit their post to say that the item(s) has/have been taken and post the name of who has taken it.
After that you PM them with your name address etc.