Pinned posts are Page posts that admins have chosen to display prominently at the top of their Page. A pinned post always appears in the top left of a Page’s timeline and has a flag in its top-right corner. A post a Page admin pins to the top of their Page will remain there for 7 days. After that, it’ll return to the date it was posted on the Page’s timeline.
Posts from people who like a Page are not eligible to be pinned posts. Page admins can only pin posts created by the Page.
HOW TO PIN POST TO YOUR FACEBOOK PAGE TIMELINE
Its simple pinning post to your facebook page timeline
Go to your page timeline.
Locate the post you wish to pin.
Hower your mouse over the top right hand corner of the post you wish to pin on your page timeline.
A star and a pencil icon with the option edit and highlight will appear when you hover your mouse over the post.
Choose/click the pencil icon and select pin post. Your post will now be pinned in the top most left position on your fan page timeline, immediately below the area to post a status update.
HOW TO UNPIN POST /REMOVE A PINNED POST FROM FACEBOOK PAGE TIMELINE