Customise the Password Protect to include an image

Hello

I would like to know how I can customize the password protect. I’d like to, in addition to the text, (“These photographs are password protected. To view them please enter your password below”) to also display an image.

I am not too good with PHP and I can’t figure out how to change the functions so some help would be highly appreciated.

The website is currently hosted in a local computer for now and not on a server so I’d rather not post the link. However, I’ve just used the general Password Protect function within the admin area…

Many thanks