How to make a header image that spills out of the header box on one side

I have designed a header image that spills out of the header box area on the left side (where the left sidebar would be if I were using it). I want to have the top of the right sidebar, the page title, and the beginning of the body text start parallel to the spilled-out part of the image.

In case it matters, these are all static pages, not a blog.

I hope this makes sense. If there's a way to post a jpg I could put up a sketch to make it clearer.

I hope it's possible to do this!

Beginner here, teaching myself CSS.

Thank you for all help!!!

Do Mi Stauber