Edited:
I think you are trying to do as done in this DEMO
There are three states of a button: normal, hover and active
You need to use CSS Image Sprites for the button states.
See The Mystery of CSS Sprites
/*CSS*/
.imgClass {
background-image: url(http://inspectelement.com/wp-content/themes/inspectelementv2/style/images/button.png);
background-position: 0px 0px;
background-repeat: no-repeat;
width: 186px;
height: 53px;
border: 0px;
background-color: none;
cursor: pointer;
outline: 0;
}
.imgClass:hover{
background-position: 0px -52px;
}
.imgClass:active{
background-position: 0px -104px;
}
<!-- HTML -->
<input type="submit" value="" class="imgClass" />