Make a new page template

Hi, I am trying to make a new page template so that pages made with this template have a different background image to normal pages on the same website.
The way I have it at the moment is I have the normal pages set up, and brochures for machines we sell open up in new tabs as PDFs. The trouble with this is that Google isn’t searching the content of the PDFs so our SEO ranking is not as high as it could be. I want to make these brochures as web pages so that Google can index them for us. So I need a way to make these “Brochure pages” different to “Other pages” on our website.
Hopefully someone can help, any suggestions are appreciated.
Thanks in advance!