You can access your Private Message mailbox in two different ways.
The first way is if your on the Home page www.aquariumadvice.com
on the right side you will see a nice message welcomeing you to the site. It will say "Welcome, Sadie" Under that you will see some links. One of those links is to view your private messages.
The second way is even easier. At the top of every page is a link bar with many links. In the center of this bar you will see one for your Private message mailbox. It might say "No new messges" or "You have 1 new Message" or something like that. It will be to the left of the Chat link and to the right of the Memberlist.