This is probably a silly question, but I'm literally a beginner in
administering sharepoint server. One of my IT guy had been layed off
and I had to take over this for the mean time...

Anyways, I've read several books and googled it but for some reason
there is no clear way of managing users in our sharepoint server. We
have the domain users, which I can manage in our domain server. but we
have another set of users that can login externally through ssl, and I
can't find it anywhere, where can I change their password and create a
new one?

I know this is probably a simple direction, and I would totally
appreciate all the help anyone can give