How do 'pages' work?
The easiest way to get your head around how pages work is to think of them as a family, or a tree. Pages on the same level are considered sibling pages, and pages a level down are considered child pages. The converse is true as well: pages a level up are considered parent pages. Use this friendly structuring logic to host associated data of a static nature.
Adding pages to your site
You can add pages from either the sitemap, or from any page in your site. While you are editing a page simply add another page, and then check the relationship guide to ensure that you are adding the new page on the level required: either a sibling page or a child page. Use this logic to structure a site, and then return to any page via the sitemap to manage content on your pages.
All pages are re-orderable too: simply visit the sitemap and hit the 'Reorder navigation' button. Now click-and-drag any pages to the location you require it to be.
Deleting a top-level page
Tank does not allow you to delete a top-level page (that contains child-pages) which is the case with most contact pages. Navigate to the child page first (e.g the thanks page), delete it, and then navigate to the top-level page (the contact page) and delete that next.