HTML CSS Textfield Image Submit Button

Please look at my login form <[login to view URL]> I have placed an image inside the password box to act as the login button but cant work out how to make it a functioning submit button. ## Deliverables Please look at my login form <[login to view URL]> I have placed an image inside the password box to act as the login button but cant work out how to make it a functioning submit button. This idea has been copied from [[login to view URL]][1] , they have a login form on their main page which has this feature. I did try to work it out by trawling through their source but failed and gave up. My HTML file is attached. Can you make the image into a submit button? Chris