Help about custom payment metod !

Im using opencart 2.1.0.1, i need a custom payment module, so i created/dplicated the bank transfer method following this -
http://forum.opencart.com/viewtopic.php?f=113&t=30653 and everything is working as well.

The module which im making is for leasing plasn about the products, so what i want is simply to show a small leasing table inside the payment section as shown on the picture.



I have the html/css code, but were i must implement it exactly? Also i will make it wit radio buttons, so i want the admin to recieve information which exactly options was selected by the buyer?

Thanks for the help!