You can find more information about promoting posts at Facebook's Business Resources.
You'll need to switch to a Business Profile..
You'll also need to be an admin of the Facebook Page associated with the Business Profile.
Promoted posts must also abide by Facebook's advertising policies.
To promote a post:
Right-click any post of yours, then select
Promote… from the contextual menu.
The Promote window will appear with your chosen post ready to configure.
Once you've confirmed your promotion, it will be reviewed to ensure it meets Facebook's ad policies. Promotions are generally reviewed in 60 minutes, but in some instances, the review process may take longer. Your promotion will begin running after it's been reviewed and approved.
To view your current, existing, and expired promotions:
Promotions item that appears at the top of your Activity.
To delete a promotion:
When viewing the promotion's details, click the Delete button in the title bar.