Community theme buddy groups meta tag

a2zhomeschool.com, want fill in the meta tag description that is currently coming up blank http://a2zhomeschool.com/groups/tennessee-homeschool-group/feed/

see code on above page. I use joost SEO plugin.

I imagine a custom field, and a piece of code in the theme? Where in theme to put code, and where do I create the custom field or associate it with the groups.

If you have a plugin I could not find ok to.

david