php in xml i think

Hi

I'm new here so please go easy on me, I'm also no good at coding so, this is what i think i want to do
i have an xml file here: http://www.golf-finder.net/mediaplayer/player20.xml

what i want to do is pass a advert tag into the xml file so as i can display 300*250 adverts as pre and post roll adverts to here: http://www.golf-finder.net/mediaplayer/videotest21.html

can anyone help me with this, i think i have to setup a php page with the advert tag in that and pass that php file into the <location></location> of the xml file ?????

if this helps the ad tags are either iframe or javascript, can post them if needs be?

Thanks

Dave