I was just about to give you an answer and I have been pipped to the post.
Yes, there is. Go to Inbox at the top right. Click on it and you get the PM page. And if you get one there will be a number next to the word Inbox to warn you. I'll send you one so you can see for yourself.
Up at the top of the page is a tab called INBOX click on it and another page opens up. Over on the right hand side click on PRIVATE MESSAGE box which is highlighted in blue. Type in person's name - no capitals, no spaces unless in name shown as the person's avatar.
So to Jan it is hightechgrammy - then write your message in body of message. Love Chris