To add a menu to your site, open the Block Library > Menu and choose the kind of menu you prefer. To change its settings, push the Content button.
Menu Items Settings
Menus can be put together by typing in item names and links or adding them from the Page List.
Menu Items List: When you enter a URL, you can use the absolute address of the page, the one that includes http://, or the relative one – just its name, e.g. page7890.html or about.
Page List is the list of the pages you have on your site. They make the basis for the menu. The pages you select will be menu items. Their order will correspond with the order of the pages. You can change the item order and its name as well as give it a special short name or a special URL in the settings of every individual page.
How to create a menu for all the pages there are
To create a menu for all the pages you have on your project (site), add a new Page, put a Menu Block there and configure it. Then go to Project Settings > More and designate this page as a Header. After that click on Publish All Pages.
How to navigate within one page with a menu
To create a menu for navigation within a single page, spell the corresponding Block ID in the links (the links should look like #rec2081259). Block ID can be found in Block Settings.