Resizing ? how to?

hi
i got a problem , i wanted to add my google adsense codes in something like box and i used this code to do it.
div class=””widgetcontent””
google adsense code
/div

but it looks like -> http://img180.imageshack.us/img180/3894/adsiz.jpg

how can i resize it ? i changed my google adsense width but nothing changed..only my google advertisement got smaller but that box which covers it was same. please help..