PeejAvery! The code u ve sent is working fine (Thanks) . but fruitless for me.
Here is the short description of my requirement and issue...

JS file -----------------> Web Page #01
|
-----------------> Web Page #02

JS file displays the Banner and Background combination by the help of these 2 web pages. Code details are

1) Web Page #01 displays Banner in iframe,iframe attributes are set by JS File

var url = 'http://www.myWebSerer.com/WebPage01.aspx'

var oIfrm=document.createElement("IFRAME");
oIfrm.setAttribute('id','iframe1');
oIfrm.setAttribute('src',url);

2) Web Page #02 sets the background

document.body.background = 'http://www.myWebSerer.com/WebPage02.aspx';

the concerned thread's URL is
"http://forums.mozillazine.org/viewtopic.php?t=630475&highlight="
please visit for me.