I have never tried to load my ST_Anything project on a SONOFF Dual relay device (because I do not have any SONOFF devices!) Since it is just an ESP8266 based board that can be flashed with your own firmware, ST_Anything_ESP8266WiFi.ino (with modifications to only create 2 ‘switch’ devices, of course) should run on it, but no guarantees.
Here is a tutorial put together by another ST user which shows exactly how to integrate a SONOFF with ST (albeit without ST_Anything 
) Still, he does a nice job with a detailed Youtube video. This may be the easiest route.
Since you mention you’re a novice, I recommend you buy a NodeMCU V1.0 ESP8266-12e board, a large breadboard, jumpers, some LEDs, and some buttons to create a small system to play around with. This will help you get a good understanding or basic circuits with no soldering required.
Here is the board I use, which can be programmed with just a standard USB cable…