I think this is quite similar to phpBB, but I will put it here just in case new members can use the information.
If a member has chosen to receive PMs, the easiest way to send them one is by clicking on the small green scroll symbol

situated at the bottom of their Profile window on any given posting page of a topic. If you go into the more detailed page of their Profile by clicking on the member's name, you will also see a text link which has the same function near the bottom of the Summary, under "Additional Information". Another way to send PMs is by going into your Messages area and clicking on the "new msg" button, top right.
If you have a new PM, it will be visible to you after logging in, via the announcement at the top of the forum page, just above the main menu. It will say something like
"Hey, krystal, you have 25 messages, 1 is new." The quantity of messages is always highlighted in blue. This is a link which when clicked will take you directly to the in-box where your Personal Messages are located.
You can elect to have a pop-up window announce your new Personal Messages while you are logged in, or you can select to have e-mail notification. If you want to cover all bases, enable both!
By default, a copy of all received messages is saved in your Inbox (of course

), but if you want to save the messages you send, you should click the option bottom left on the Personal Message screen (Save a copy in my outbox)
before sending it.
However, if you want
ALL sent messages to be automatically saved in your Outbox - which is definitely the easiest way - you can configure this (and add the above notification methods) via the "Personal Message Options" page which is linked in your
Profile area. You simply check the option
"Save a copy of each Personal Message in my outbox by default."