Actually, that link won’t help too much, because if you check out the HTML structure of the page, the tagline is there, but it’s being hidden via CSS:
.site-description {
display: none;
}
It’s a deliberate decision by your theme’s authors.
You could show it by using some custom CSS:
.site-description {
display: block;
}
but your header is designed under the assumption that the tagline won’t be showing, so it looks kind of bad. You might be better off making a child theme, copying header.php to your child theme’s folder, and editing it so that the tagline “fits” better within the header’s design. That’s a bit out of scope for this forum, though, so if you’re not confident in that, you might seek out help at https://jobs.wordpress.net/
