PowerStore does not support connecting directly to your bank.
It uses either Paypal Payments Pro US or Auuthize.Net as the payment gateways.
You would need to follow your banks Integration Guide to modify power store to connect to your bank:
We do not support this sort of modification of PowerStore.
The PowerStore requirements are:
A host that supports PHP and MySQL.
and an SSL certificate.
The getting started guide on the PowerStore support page will help you get started using PowerStore: