Adding messages and images to group
After creating a group you can add as many messages as you like inside it. Click the "create new snippet'' icon to create a new snippet.
Messages with links
To create messages with links simply copy / paste the url in the message box. When you do a preview of the link for Facebook and Twitter will appear on the left side. After adding the link you can type any message you want. For your convenience a character counter for Facebook and Twitter is available below message box.
Messages with images
You can attach one image per message by clicking the "Attach Image" icon. You can attach jpg and png. After creating the message click "Save" to add it the group.
Why you can't modify the link preview title, description and image? Facebook
As of July 18, 2017 Facebook removed the ability to customize link metadata (headline,description, image) from all link sharing entry points. If the website is optimized with Facebook correct metadata code then the link will appear properly. Sadly this is beyond our control.
Instructions for webmasters
If you want to have the correct link preview for your website, make sure that you have Open Graph optimized on all your pages so you’re publishing the correct information. We will try and show you the best link preview that we can, but if you want to double-check any of your URLs prior to going live, we recommend inserting your URL into Facebook's Sharing Debugger. For more information on Open Graph, we recommend visiting Facebook's Open Graph Best Practices and Guide for Webmasters.
What tools can help me customize or manage my Open Graph information?
For all WordPress users, we recommend using YoastSEO. For more information on optimizing your social messages inside of Yoast, check out https://yoast.com/social-media-optimization-with-yoast-seo/
For Twitter if you want your previews to be optimized you need to use Twitter Cards with the appropriate meta tags on your website. For more information visit https://dev.twitter.com/cards/overview