Standard header options
Appearance > Customize > Site Identity
Set the sites logo, title and tagline
Appearance > Customize > Header & Footer > Start Here > Header
Setup what’s displayed
Open a page > Page Settings > Site Settings > Header
Setup other aspect
Creating a custom header
Templates > Theme Builder > Header > Add New
Select one of the template designs to get started.
When you save it, set it to be included for the entire site (Display conditions > Entire Site)