If you used Fastpay last season with a matchday pass, you will need to collect a new one from the ticket office. The ticket office is open Monday to Friday, 9 until 5 and match days from 9 until kick-off. Then just register the new matchday pass to your Fastpay account at http://blues-fastpay.com.
If you have a matchday pass from this season, simply register your pass at http://blues-fastpay.com.