Hello Guillermo,
To move your picture to top, you should change
style=”background-position: 50% -50px;”
to
style=”background-position: 50% -50px;margin-top:20px;”
Of course, you can use any image you want. If you want to change that picture, add the CSS rule below to your Appearance > Customize > Custom CSS section:
.blog .hero {
background-image: url(http://www.fantasticus.nl/sandbox/wp-content/uploads/2017/08/Fantasticus-Marco-Borggreve-copy-3.jpg) !important;
}
Don’t forget to change the URL of image to desired one.
Thanks,
Piotrek