Add description in the css – header impossible!

Hello everyone!

I am trying since month to add correctly a description in the header (in the css files) and each time I am trying to modify it, I have an error code in my blog (theme coraline)!

from now, the header is like this:

// Add the blog name.
bloginfo( ‘StrategicalBlog’ );

// Add the blog description for the home/front page.
$site_description = get_bloginfo( ‘Le blog Méchamment Intelligent!’, ‘display’ );
if ( $site_description && ( is_home() || is_front_page() ) )
echo ” La Stratégie appliquée à tout! “;

In my website: http://strategicalblog.com, you can see the title and the line below is the same, instead of having a tagline below :/

Someone, to help me to change this, please?

Thanks!!!