Before we start…
Many of my clients use Mail Chimp to send out campaigns (newsletters) to their target audience. While creating a campaign in Mail Chimp, you have the option to include a 'Social Card' which includes a pic, title and a sentence or two.
Social cards are specifically designed to share the information you'd like your audience to see when your campaign is shared on social media accounts, like Facebook. Use the link below to learn a bit more about custom designing social cards.
Back to the question, "But how do I…"
It's a great way to double the value of your campaign (newsletter) by posting it on your social media accounts.