Enrolment

I used Moodle extensively at UW-Madison until we got Campus (boo). Anyway, I am teaching at an arts HS and set up a Moodle on the cloud--which I really appreciate--for 45 students in a class.  This is the part I never had to do: enroll and get them access. I used their emails to enroll them but they say that they can't access the page.  I set it up for them to be forced to change their password but all but 2 people told me they can't even access the page to change the password.  Did I do something wrong?  Is their password my password--that seems to be what was happening but concerns me that they can access my privileges.