You can log on to www.irctc.co.in and book your tickets using credit card. At some PRS counters in big towns and cities there are exclusive counters for credit card. You can go to those counters and also book your tickets. Usually the credit card transactions will attract a transaction fee of 10 Rupees by the IRCTC per transaction and about 1 to 2% of the value of transaction by the credit card issuing company.