Some details will already be filled in here, we just need fill the remainder.
Incoming mail server
Enter the details supplied to you, likely mail.yourdomain.com.au
Username
Enter your full email address.
Password
Enter your password.
Outgoing mail server
Enter the details supplied to you, likely mail.yourdomain.com.au
Username
Enter your full email address again (it does suggest this is optional, but it is required)
Password – Enter your password (it does suggest this is optional, but it is required).
Carefully re-read
Have a look over it, make sure there are not typos. Easier to fix them now than troubleshoot later.