=============================
What...exactly, are you calling a "digital background"?
If you are asking how to place the main
subject of a digital image on a different background...this would be
accomplished
by creating a "cutout" (think...paperdoll)
and placing the cutout on the image that will be the new background.
The following links are two original scans
and a third image which is a composite of the first two. This was
accomplished using cutouts.
(Original A)
http://tinyurl.com/b67i
(Original B)
http://tinyurl.com/b67h
(Composite)
http://tinyurl.com/b67k
I'm not familiar with ArcSoft Photo Studio 5.5 but you need software
with the tools
to create cutouts and layered projects.
If you would like to try a different program....
Microsoft Digital Image Starter Edition 2006
is a downloadable 60 day trial version with
much of the functionality of MS Digital Image
Suite 2006.
Once your 60 day trial period has ended, the
program will de-feature to minimal functionality.
Unlike the retail version...the trial does not
have the ability to create VCDs and does
not support RAW files.
Microsoft Digital Image
Starter Edition 2006
http://tinyurl.com/8x6ea
Be aware that it's a 109 MB download....