Hello,
Thank you for using our theme!
Watch the video tutorial on how to create the menu https://youtu.be/OnxkixHtVLI
Read here how to add the product categories to menu https://docs.woocommerce.com/document/docs-menus/#section-6
And watch the video tutorial on how to edit the header https://www.youtube.com/playlist?list=PLMqMSqDgPNmDu3kYqh-SAsfUqutW3ohlG
Let me know if you need any other help.
Regards