make search button an image in twenty ten?

theres no searchfrom.php in twenty ten. apparently its all inbuilt into general-template.php

thats all well and good ive found it, and ive gone to change it to an image, and it hasnt worked. does anyone have another method? or a piece of code i can use please? thanks alot, its annoying me so much.

heres a link to my site: https://www.touchercrds.com/blog/wordpress/