Customize menubar

sure! (probably)

Please post a link to your site.

This CSS will do it. If your theme has a custom CSS feature, use it. If not, install the plugin “Simple Custom CSS”.

.menu {
    float: none;
    display: inline-block;
}
menu-container {
    display: inherit;
    position: relative;
    text-align: center;
    width: auto;
    float: none;
}

If you have other questions about your theme, please visit

https://wordpress.org/support/theme/comicpress

How did you “put it in”? Your theme has a custom style sheet at http://www.backwardsd.com/wp-content/uploads/css/custom_style.css but the CSS is not there.

If you have any caching plugins, please clear all caches.

My bad… that should be DOT menu-container .menu-container