Share Permission

I’ve set up a home network using a workgroup model. I
want other network users to be able to access a share
that I’ve set up on one of the desktops hardrive. I can’t
seem to find a way to set permissions for specific group
or users with thissetup. For example, I would want group
x to have access and not group y or user x to have access
and not user y. In a domain model, the options exists to
add groups that would have access to this folder.
However, in workgroup this option doesn’t seem to exist.
Any ideas or thoughts will be appreciated.
.