By “tabs” you mean Pages in the menu. A heading is a “section title” inside post content, so I’m trying to understand what you are doing.
If you want more control over your menus, try using Appearance > Custom Menus. Appearance Menus Screen on the WordPress Codex.
For more specific help for your Theme, contact the Theme author.
Thanks Lorelle for taking the time to respond. I’ll give that a try. I have also just got the book WordPress for Dummies so no doubt that will help.
Regards
Kellie