How can I hook a child theme into twenty eleven

Hi all,
I followed a tutorial,
– created the child-theme’s directory
– edited a file called style.css with

import url(“../twentyeleven/style.css”);

h2.entry-title {
font-size: 10px;
}

~ edited a new function.php file, but …

How can I hook my new style.css into the other twenty-eleven stuff?

Regards
CJC