We have over 80 themes at wordpress.com and few older themes like yours do have an automatic display of a an About entry in the default sidebar display. But that’s not what this blogger above asked about. He asked about a static page he had already created and titled “About”.
He has a theme that does not have either Page tabs or a horizontal navigation menu. He needs to use a Pages widget in that theme in order to provide links to access Pages and sub-pages.