As @PeteKnight said… the RPI, while supported, is not well documented with Blynk.
Mostly you, alone in the dark, lit by LCD backlight, looking at the limited examples and spending hours experimenting with syntax… oh, wait, that is me not you 
You have two primary choices that seem the best option for that hardware with Blynk
NodeJS - https://github.com/vshymanskyy/blynk-library-js - I have some JS examples here - NodeJS Blynk - Code Examples for Basic Tasks (Work in Progress)
Python - https://github.com/vshymanskyy/blynk-library-python - I have posted a few Python examples in this forum, but have not compiled any into a topic yet.