ez Form calculator basics

Hi, I have downloaded the free version of this calc, and I am prepared to buy the full version if I need to. But I don’t see any basic step by step tutorials on how to get started with it, nor can I find a contact us anywhere. SO I’m not really excited to buy a product that there seems to be no support to.

So if someone can point me in the right direction to where I find this info, or if someone can help with the very simple calculator I’m trying to make.

Basically all I want to do is have 3 entries lets call them entry A, B & C.
A = Number
B = %
C = Number
All I want to do it =(AxB)/C and get the result.

But I don’t seem to be able to find anything to show me how to do this. Any assistance would be greatly appreciated.