Linking Header Image

I’ve been searching for this topic and gone through some threads using all the suggested codes and nothing worked.

I’d like to make my header image to be linkable. What code do I use and which file name do I modify?

The header image name in my theme is “bodybg.png” – I know, it’s not a jpg or anything, that’s what the theme creator did, so I have no clue.

If you could provide me with the code plus the image name or whatever else necessary, that would be so awesome.

Thanks!