I am using a template for 5 pages but want a different background image on each page. I know there must be a way to do it, but I don't know how to make the page background and "editable region".

create a editable region on the head part.

and then make a css style for body and specify the background image there

do the same for the 5 pages

<style type="text/css">
body 
{
background-image:
url('image.jpg')
}
</style>

wow fast response! Thanks, I will do that!