ad code

how do i add an ad code to the html source code from within the dashboard of my blog? the code is from adgridwork.com.

<script type=’text/javascript’>
<!–
var sid = ‘277’;
var title_color = ‘000000’;
var description_color = ‘646360’;
var link_color = ‘7FBE00’;
var background_color = ‘ffffff’;
var border_color = ‘dddddd’;
src_str = “https://www.mediagridwork.com/p.php?sid=”+sid+”&tc=”+title_color+”&dc=”+description_color+”&lc=”+link_color+”&bgc=”+background_color+”&bc=”+border_color;
document.write(“<iframe id=’adfrm’ name=’adfrm’ src=” + src_str + ” scrolling=’no’ height=’90’ width=’200′ frameborder=’0′></iframe>”);
//–>
</script>