如何为在线交易创建支付网关?

In my web application there is an online transaction system for online reservation. I have no idea about how to implement this, i.e when an end user wants to do reservation, a form has to open showing different banks, by selecting bank, user will be allowed to enter his/her card credentials and I have to send this to third party payment gateway vendor and has to receive information from that party regarding the transaction status. In my web application there is an online transa