Thanks for your response Ryan,
I always took the URL of the chosen article. I have mentionned the root adress to let you check if something goes wrong somewhere on the blog.
After writing the Sample Embed Code, I do not see my tweet with a card added 
If you could explain me what I’m supposed to do once the validator has approved my card, it would be great :))
Thanks a lot for your time,
Kindly,
Nicolas