add header to the xml

i want add header to the xmlelement URL, how can i add this?
conn.UrlCategoryAd = m.serviceurl+"/GetAdvertisments/"+m.videoid+"/"+m.urlurl+"/1"
xml=CreateObject("roXMLElement")
http = NewHttp(conn.UrlCategoryAd)
rsp = http.GetToStringWithRetry()
m.nouse = xml.Parse(rsp)
xml.addheader("xyz","abc")