Simply put, Edge One-Pager is only a simple page with categories of each part of the page with different sections. Full height should be set for these sections in order to have the best style of these sections.
Use this link: http://webnus.net/deep-premium-wordpress-theme-documentation/visual-composer/ to know how to use Visual Composer and refer to this link: http://webnus.net/deep-premium-wordpress-theme-documentation/king-composer/ for King Composer.
First, you should create a page, check this link: http://webnus.net/deep-premium-wordpress-theme-documentation/create-new-page/ then, by adding a section, you can complete the page that you are creating step by step. After creating each section (our suggestion is full height section for better appearance) go to page option settings and enable the option Edge Onepager. For more information on page option you can check this link: