Prova a vedere se questo ti va bene.

Codice PHP:
<html>
    <head>
        <meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
        <title>Prova</title>
        <style media="all" type="text/css">
            html,body
            {
                    margin:0px;
                    padding:30px;
            }
            #centralone_home
            {
                    width: 640px;
                    height: 626px;
                    margin: auto;
                    background:silver;
                    text-align:left;
            }
            #sponsor
            {
                position:absolute;
                width: 175px;
                height: 120px;
                background:lightgreen;
                margin-left:610px;
                margin-top:50px;
            }
            #contenitore
            {
                width:100%;
            }
        </style>
    </head>
    <body>
        <div id="contenitore" align="center">
            <div id="centralone_home">
                <div id="sponsor">SPONSOR</div>
            CENTRALE
            </div>
        </div>
    </body>
</html>