Please show me where

The meta description is the normal snippet that Google shows on their results pages. If you don’t have one, they’ll usually take a relevant sentence from your text on the page, or they’ll pull in a description from elsewhere on the ‘net that might be considered more relevant.

WordPress doesn’t support meta tags out of the box, so you’ll need to install a plugin, like all-in-one-seo or similar: http://wordpress.org/extend/plugins/search.php?q=meta