Can’t login new user

I want to see how various classes of users will see my blog, so I created users Author, Contributor, Subscriber, etc, and then switched from Firefox to IE and tried logging on as each of them, but I keep getting Error: Incorrect password

I know that when a user initially registers he is sent a cryptic password, when he can use to login and then change, but I would have thought that if Admin created them and assigned the password, that step would be bypassed.

Do I have to give a unique email address and then go read the assigned password on these users?

I tried just giving it my email address over and over, but I would not let me use it, since it was already used