Header Image
Replace the website title with an image (logo or a banner).
To replace the website title with an image, go to the Layout view in the Blogger Dashboard and click the "edit" button on your Page Header gadget.
Provide the URL of your picture or upload it from the computer and then select the image placement:
“Instead of title and description” or “Behind title and description” (serving as a text background image).
Choose the placement of the header image on the page
and position the Page Header gadget accordingly:
centered / full-width
To customize the header background color, go to:
Advanced ⟶ Backgrounds ⟶ "Header".