Under Add To Site in your Toolbar, you will see Add A New Top Level Page. Here you can add a new Top Level page if you have not already reached your limit of 4. If you have reached the limit, rather than displaying New Custom Page it will show that you have already reached the limit and will advise you to reuse other pages.
To add a new Top Level page:
All new pages come with a Text Block for you to edit, plus you can add new content as you would anywhere else on the site.
Top Level pages will also list all of the Sub Pages created below that page along with a snippet from the first Text Block on that page. All other content items you have added will appear below these snippets.