It appears as though you're asking how to customize the desktop for
two users, even though you've left most of your question out of the
body of your post. Rookie mistake, but easy to fix next time.
Anyway, Windows will happily allow a customized desktop for each user
account, so the answer is to create a separate account for each user.
Once you do that and inform each user to log into their own account,
they'll see that they each have their own desktop and can customize to
their heart's content.