Since Divi 4 was released, Divi supports website templating. It supports building custom headers, footers, post templates, archive templates, etc.
This is how you create a Custom Global Header in Divi.
- Go to Divi >> Theme Builder
- Add Global Header
- Build Global Header
- Build from Scratch
- A section is automatically added. Insert Row.
- Add Menu module and select the menu you want to use. You can create menu in Appearance >> Menus
- Start customizing the section, row, and module. You can add another section, rows, and modules.