I can.
Let's say you want to sell a Paramount Defense ring (Shortened to Para Def usually).
You will type something along the lines of..."Selling Para Def 2 Def Pots.
In that example you are selling a Paramount Defense Ring for 2 Defense potions.
So then the person trades you (or you trade someone else you see buying one). You select the Ring in the trade screen, they select the 2 Def pots ( Or w/e you want for it and they are willing to pay). Then when all the items are accepted, and you are ready to continue, you press accept trade. After both accept the trade, it is done and you have the other items, he has the Ring.
You initiate a trade by either:
1: Clicking on their name in the "lock List" or the panel on the bottom right that displays player(s) names depending on how close you are to them (closer people show up first in the list).
2: Typing /trade Name
ex: /Trade TonyDee
This would trade me if we were in the same server/realm
3. The person trades you, and you accept trade by clicking on the accept trade button that pops up over the lock list.