Hi,
If your bank gave you a plugin to integrate HikaShop with their payment gateway solution, then it's easy to setup:
1. install the zip via the Joomla installer.
2. go in the menu System>Payment methods of HikaShop and create a new payment method and select the payment plugin you just installed and you'll be able to configure it with the merchant identification information that your bank provided you.
If they didn't give you a plugin to integrate HikaShop with their payment gateway solution, but simply an "integration kit", it means that basically they told you to develop your own payment plugin for HikaShop. If you're not a developer, that would require hiring one to have that plugin developed for you (unless such plugin already exists).