Logging into the new Atrium application is generally self explanatory.  If you have experience logging in to Atrium 8, then you already have the necessary credentials.  If you have not logged in to Atrium 8 before, then an Atrium Admin will need to provide you with those credentials.  The credentials will consist, typically, of the email address you will use as your ID and a temporary password assigned by the Atrium Admin that you will need to change the first time you login. 

The Atrium 10 login screen looks like this:

You will note that, should have forgotten your password, there is a link to click to request a new password.