Tattoo Studio is a single page website template. Main menu is generated by the template because all these pages are on your front page. They aren’t additional pages. They are the parts of your front page. When you click on any of the main menu item (Red Menu), as you will see, url of your website will not changed. Because you are still in the same page.
When you click on a sub menu item (Black Menu), url will change because you will go to an additional page;
If you want to add a page to the main menu (red menu), just add a new front page section;
If you want to create a sub menu (black menu) for your additional pages like featured articles,external links etc.
1) Go to Menu manager
2) Create a menu (please look at the following screenshots)
3) Don’t forget to select “submenu” module position