NPressive recommends Stripe for credit card payment processing. Their approach to transaction fees is simple—2.9 percent plus 30 cents per transaction. You won't have to worry about recurring or surprise fees. Stripe also provides options to accept Bitcoin and ACH/eChecks for even lower transaction fees.
There are several features within NPressive that utilize and require a payment processor like Stripe:
Registering for an Event that requires a registration fee
Submitting a Forms/Application that collects an application fee
Providing a Donation
Opening Your Stripe Account
Visit Stripe's website and signup. Follow their instructions to setup the account.
Define your checking account for deposits. Funds are deposited every rolling two days.