This is the documentation for ConfiForms Server/Data Center app
However, this might also work for ConfiForms cloud and in most cases it does. But please see this page to understand the differences between server and cloud versions of the ConfiForms app.
Simple tutorial on how to use ConfiForms Field Definition Rules#Showfield and it's counterpart ConfiForms Field Definition Rules#Hidefield ConfiForms Rules for Field Definitions to show and hide fields conditionally
Consider a form that has few fields like this