If you haven’t already created an offer on your Page’s Timeline, click Offer, Event + button and click Offer. Fill out the details and select the expiration date for your offer and click Create.
Go to your Facebook page after you have logged on and click “Build Audience” at the top right of your page. Click on “Use Ads Manager” and click “Create Ad” at the top right of your page. Click on “Offer Claims” from the list. Select the page where you posted your offer and in the second box select the offer you want to promote. Choose your audience target, set a budget and place your order.