I want to add an image, instead of the default button.
I already have a CSS class for the image, will this work?
Although you can "replace" a button with an image using the following CSS...
.className {
background: url(http://sstatic.net/so/img/logo.png) no-repeat 0 0;
border: 0;
height: 61px;
width: 250px
}
...the best thing to do here is use an ImageButton control because it will allow you to use alternate text (for accessibility).