Mike if you hover your mouse over the name of the person you want to write to (on the left hand side of the screen where their message is) and click on it a small menu will give you options. One of them is 'Send PM' I think which is a Personal Message. Simply write your message and click on Post at he bottom of the screen.
If you want to see any replies to messages go to the very top of the screen near your name (on the left) are two options - [Unread posts] and [New Replies], click on New Replies.
Give those a go and if you're still having trouble let me know.
Fiona
