How to add a background image in css when it already has a background image

How to add a background image in css when it already has a background image

Hello Friends,

This is my  HTML

<li id="myemail" class="myemail"> <a href="a.php">TEXT</a></li>


CSS
.myemail{ background-image:url(/hcj/images/email1.png);  background-repeat:no-repeat;  }
.myemail:hover{ background-image:url(/hcj/images/email2.png); background-repeat:no-repeat;   }
.myemail3{ background-image:url(/hcj/images/email3.png);  background-repeat:no-repeat;  }


Jquery Code


$('#myemail').removeClass('myemail').addClass('myemail3');

$('.myemail').css('background-image','url('+ /image/email3.png +')' );.



I am trying two jquery way of changing the background image when a certain condition is met in php i.e. 

I am trying to remove a class and add another class 

OR 

I change the css background image 

but neither of them are working for me, please help me as to where am I going wrong.

Thanks in advance.....