طريقة عمل ذالك

/*-- editor background custom --*/
.sceditor-container textarea, .sceditor-container iframe {
    background-image: url("http://i37.servimg.com/u/f37/17/30/21/98/help-a10.png") !important;
    background-position: center center !important;
    background-repeat: no-repeat !important;
}