CSS Help!

[lakaroth]

Hi guys, who can help me with a simple modify in CSS?
I'm using "Aryze" template, and i want do a simple modify:

The original image BLOCK is like this:
938px
400px



I want do a big image horizontally larger all over the screen like this:



Now... in Style.css there's this:

Code:

/*******************************MEDIA*********************************/

#mediaBlock
{
    float: left;
    background-image: url(../design-Props/mB-bg.png);
    background-repeat:no-repeat;
    width: 938px;
    height: 400px;
    margin: 5px 0px 10px 10px;
  border: 1px #fff solid;
  background-color: #fff;
    padding: 0px 0px 0px 0px;
}

#mediaBlock h1
{
  text-indent: -9999px;    
}

.mediaBlock
{
    width: auto;
    height: auto;
    padding: 0px;
    margin: 0px;
    border:;
}

/*-------------------------------------------------------------*/

I'v tryied to modify without success, how can i do it?
Best Regards