Adding 1stPayGateway
To accept payments through 1stPayGateway, you will need to add them as a provider.
Getting an account
If you need to sign up for a 1stPayGateway account, you can register for an account here.
Adding 1stPayGateway to payFURL
You can use following instructions to get Gateway Information.

1stPayGateway Login Url
You'll need your TRANSACTION CENTER ID and GATEWAY ID.
You can use this to add 1stPayGateway as a provider in payFURL. Go to Providers, New Provider and select Provider Type 1stPayGateway:

Test account
You can also use test account from the documentation, page 56
Transaction Center Id = 1264
Gateway Id = a91c38c3-7d7f-4d29-acc7-927b4dca0dbe