centrar?

[hades87]

Código:

body{
background: #FFCC00;
}

.cabecera1{
    position: absolute;
    z-index: 1;
    left: 249px;
    top: 0px;
    width: 180px;
    height: 105px;
    border: 1px solid #FF6600;
}

.cabecera2{
    position: absolute;
    z-index: 1;
    left: 431px;
    top: 0px;
    width: 667px;
    height: 65px;
    border: 1px solid #000000;
}

.menu{
    position: absolute;
    z-index: 1;
    left: 431px;
    top: 66px;
    width: 667px;
    height: 40px;
    border: 1px solid #000000;
}

.lateral1{
    position: absolute;
    z-index: 1;
    left: 249px;
    top: 107px;
    width: 181px;;
    height: 65px;
    border: 1px solid #000000;
}

.lateral2{
    position: absolute;
    z-index: 1;
    left: 249px;
    top: 173px;
    width: 181px;;
    height: 124px;
    border: 1px solid #000000;
}

.lateral3{
    position: absolute;
    z-index: 1;
    left: 249px;
    top: 299px;
    width: 183px;;
    height: 400px;
    background: #FF6600;
}

.pie{
    position: absolute;
    z-index: 1;
    left: 249px;
    top: 699px;
    width: 851px;;
    height: 70px;
    background: #FF6600;
    text-align: left;
    font-family:"Comic Sans MS";
}

.centro{
    position: absolute;
    z-index: 1;
    left: 431px;
    top: 107px;
    width: 647px;
    height: 565px;
    border: 1px solid #000000;
    background: #FF6600;
    padding-top: 25px;
    padding-left: 20px;
}

.container{
  width: 2500px;
  position: relative;
  margin: auto;
}

este es el codigo del css.

la funcion de javascrip no la entiendo :S