You need an IT Account before you can log in to your email account.
If you are on a University student Windows PC, you won't need to log in.
Otherwise you'll see this screen:
Log in using using your University email address (or UNV\username) and password.
The first time you log in you need to change the Language to English (United Kingdom) and the Time Zone to Greenwich Mean Time (unless you are a student outside the UK. It is important that you set the right time zone, otherwise meetings in your calendar may appear at the wrong times.
Your Office 365 mailbox will now load. The screen may look slightly different If you use a browser other than Internet Explorer.