Platformio working with github sketches etc

Hello, I am new to Platformio. I am trying to use it for Arduino and ESP32 downloaded sketches and etc. I am totally lost as to how to do that. Would someone be so kind as to give me a breakdown of the steps needed. I would gratefully appreciate such help. Most of the sites I go to explain how to write a Hello World sketch and that is not a problem for me.

Sincerely,

soky157