Hi All i have now completely rewritten this post, it might make more sense to somebody now !
I found by Googling, the answer to my original question, but as i dont understand the first thing about HTML and JavaScript i am still no further forward.
That page shows an example of what i was looking for, but i wouldnt know how to use it.
This site http://unionstationdenver.com/ referred to in the link above, is a good example of the effect i would like in my RW site.
Is it an easy task for someone to make a working example that i can use in RW please ?
Tim