Contact the editor of the section you are interested in. They dont have an Add URL page or something to that effect. You will need to email the editor, present to them the page/site, tell them how great your site is and how valuable it is for About.com's audiences.
They don't care about pagerank - they care about how your website can be of value to their users. It's all about their users (which many link-obssessed webmasters have forgotten).