Hi Donna,
To be able to recieve PM's.....

1. At the top of the screen click on the message icon. (the little envelope)
 Your inbox page should be what comes up.
2. Look on the left hand side of your screen about half way down....You should see the word settings. Click on it.
A new page will come up that says message settings.
3. In the box that says Recieve or reject messages the first line.
There is a drop down menu that allows  you to choose either
Everybody
My friends of friends
Friends.

Just choose the option you wish to have.

Hope this helps