Add Image to header/top of pages on my site

Hi, I’m currently using the theme “Storto.” It’s basically a lite version of the premium theme “Gigante.” Unfortunately, I can’t upload a logo onto this theme unless I upgrade, which I don’t want to do yet! Any way we could work around this issue? Maybe a large banner across the top of my site? I searched and searched for header image/site logo plugins, but none worked correctly with this theme.

Regards,
Luke