Your account has been created by your trial administrator and a confirmation email will have been sent to your email address automatically. You must click on the link in your confirmation email in order to set up your password so that you can login.
If you have forgot your password or it has expired, you can use the Reset Password link shown below. You will receive an email which will allow you to Change your password.
When you login you can also change your password by selecting 'Change Password' from the menu above.