The PM's work. Try this as an example:
Click on the blue colored name in the left box
When you do a menu opens so click on Send a PM
When you do that a new page opens
On the left it says Add Recipient
to the right of it is a name in a box, I will try MarkOue above
Click "Add" in the little grey box to the right of the name
When you click "Add" it removes the name from the box and puts it just underneath it.Put in your subject, write your message in the big box and hit submit.
The person on the receiving end should find a red flashing triangle at the top where it says "My Stuff"

So many guns, so little time!