[eluser]James Gifford[/eluser]
Paysignet seems to be a payment gateway for processing credit cards.
I have experience processing transactions through a different service called Authorize.net.
Authorize has API documentation for programmers which I used to help create a CI library. Its not too complicated, just sending and reading a curl request. however you need to know how to format the request.
You might check to see if Paysignet has any documentation for programmers.