After you have created a sitemap, click the edit button located under the title of your sitemap in the list. Another edit button is located for your convenience in the upper right hand corner of your sitemap. Only logged in users will be able to see the edit button located on your sitemap. Shared viewers of the sitemap will not be able to see or use the edit button.
Edit your sitemap using the tools located on the left side of the editor. Drag and drop pages to position the hierarchy.