Graphic elements are an important part of every web page. A larger background with several smaller images like logos, photos, and icons is a popular solution that works great in most cases. When you start building your website, you'll very likely choose a template with a structure similar to your end goal. But you still need to tweak it.
A themed photo (if you are a constructor, a building could be the obvious choice) is definitely a more eye-catching solution than a simple layer of color. In our case, presented here, the website is dedicated to the literary works of a famous illustrator. His illustrations would be a better choice than some vaguely related photo. But his photo could be useful, too.
So the designer opted for a combination of his illustration and his photo. She did that by using two facing pages from his most famous book, where two of his popular characters are easily recognized, and then inserting illustrator's photography to visually connect the author with his imaginative creation.
The detailed procedure is described here:
https://pippi-at-home.blogspot.com/2024/04/how-to-make-composite-picture-in.html