How to add site description that shows up when posting the url ?

…f. ex. to facebook
I have the same problem as one of the other users here:

“Thank you for creating this theme.
Now, when we want to share the link on Facebook, the description area stays empty. I’ve added WordPress SEO by Yoast and tried All in one SEO (both deactivated now), but still no description shows up. I’ve also added meta description code to the header.php, but that doesn’t seem to work either.

Anyone any idea’s on how to fix this? Thank you!”

You wrote
Try using a plugin like Facebook OpenGraph Tags

I did install it but couldn’t handle it, no idea how to fix the site description with it.
I also tried several other plugins like meta description, didn’t work.

As I consider the personal info to be shown when I post my page important, please tell me where in the editor I can change it or how else to fix this.

ANdy