Thanks to my friend's @georgeboya post:https://steemit.com/steemit/@georgeboya/how-to-chance-the-cover-photo-of-your-steemit-blog-tutorial
i changed my cover photo with this:
This photo is resized to fit in my blog headers .
Photo taken under the path that leads to the highest peak "Mitikas" (2918m),
on a beautifull morning with a "cloud sea" under our feet!