In order to add a new tab to the menu of your home page, simply go to > Website > Menus:
If you wish to add this tab to your header, go to the menu already created > ... > Edit a menu. If you wish as well to add it to your footer go to > ... > Edit a menu:
You will have the list of all the tabs, where you have the possibility to add a new one by clicking on > Add menu item:
A pop-up will appear where you will have to add a title and a link (you will have here all the pages you created on > Pages. Click on >Add to add it to the menu:
Back to your list, grab it with your mouse and drag it to the desired place if you wish to switch the order of your tabs.
You can also drag and drop to add pages on sub-menus; when a page is on a sub-menu, several pages will be available under the menu:
Do not forget to click on > Save for your website to be updated.