Adding Tabs to Joomla JA Purity:
- Login to Joomla administration (your_url/administrator/)
- Go to Extensions --> Module Manager
- Click the "Main Menu" module from the list - a "Module" editing page will be opened.
- In the edit page that was opened, go to the details section at the left side of the page and change the "position" from 'left' (or any other value) to 'hornav'.
- Save
- Refresh your website, and you'll see the main menu as tabs instead of a list at the left side of the screen.
Good luck!