i need a code for blogspot

i have a blogspot and i embed youtube videos inside it but when i post the link on facebook, image of the embedded youtube video does not appear on facebook so how to make it appear
i saw others doing it but i dont know how
to be more clear ..how to make my blospot link appears like this link when its posted on facebook
http://www.alkahera-alyoum.com/v/104766/09-12-2014-cia

First of all you need this: https://developers.facebook.com/tools/debug/

Facebook caches images and things, so you have to debug your site after every change you make before testing if it worked on facebook. If you don't debug first then facebook will remember the pictures/settings it previously crawled, and any changes you make to attempt to solve this problem won't be visible on facebook.

As far as making that work, it's not that hard, but I can't remember exactly how to do it. It has to do with inserting a little code in the youtube video you uploaded. And the you insert a screenshot code in there and make any image you want be the thumbnail for facebook, and google+, etc.

Just google it, there are solutions to this out there.