Some social sites use Open Graph tags ( http://ogp.me/ ) to help identify shared pages and call out which image to display on your social site's post.
You can add a meta tag for the image you would like to use as your Open Graph image by adding in this tag with your image address in the head section of your page.
To start, Select and right click the image you'd like to use as your Open Graph image.
Select "Copy Image Address" which will copy the image file to your clipboard. Paste this image address in a text editor or in a note on your machine to save it for a later step.
Next, Navigate to the "Page" tab in the editng palette
Click the <head> section to Manage third party scripts and paste the below code below the first line of code:
<meta property="og:image" content="
Then, Go to the image address you saved from the earlier step, select it, and copy using the CMD+C (on Mac) or CTRL+C (on Windows)
You can now paste it right after the <meta property> tag we've added in the head section of our page.
To close this off you can type "/> right after the image address you've just entered. Everything should now look similar to below:
You can now "Save & Close" the head editor and then save the page through the save button or the CMD+S (on Mac) or CTRL+S (on Windows) short cut command.
Your Open Graph image should now be display the image you've selected.
Sometimes, Sites such as Facebook require you to refresh the cache on their end to activate the changes. You can use their debugger here to purge the old Open Graph data: https://developers.facebook.com/tools/debug/