To create a Header section with the Input theme, head over to the WordPress Dashboard > Pages > Add New. Give your newly created page a title. Now scroll down below & click on Header from the Page Options.

From this Page Option > Headers users can add colors for different sections of the header section & enable a sticky logo.

To add your logo to the Input theme, head over to WordPress Dashboard > Theme Settings > Header. Here you’ll have the option to add different types of logos such as main logo, sticky logo, retina logo, & retina sticky logo.

You also have the customize the Action Button from here.

When you’re done, make sure to hit Save Changes.