Header: Image or banner url home link

Hi again.
I am having the very same problem of other users, so I could notice:

I made a 940×100 banner for the header and disabled text and description viewing. Since there´s no text, url link to go back to the home page is also gone.

I would like to have a solution for this, please. Since I am not a very good coder, if someone could please specify the file, file location and line where to change or introduce such new code, it would be just great. Course, the code itself : )

Thank you in advance,
Paulo