centering add banner code (AdMob)

[Pleasant Day]

I have a web site that uses some code to put adds into the page, but my adds are not centered, whats the code to make it be in the center of the page, at the moment its to the far right for some reason, I want to try and correct that.

Here is an example of the add code, I want to center this, but leave the rest of my code on the page as it is, so I want it to only effect this add code here.

<script type="text/javascript">
var admob_vars = {
 pubid: 'd45kdzjndj45n45nj', // publisher id
 bgcolor: '000000', // background color (hex)
 text: 'FFFFFF', // font-color (hex)
 test: true // test mode, set to false if non-test mode
};
</script>
<script type="text/javascript" src="http://mm.admob.com/static/iphone/iadmob.js"></script>

This is an admob script for a web page in landscape for those that may recognise, so perhaps some of you have tried to get AdMob in landscape.