Do you know of a tutorial that demonstrates Public Private Key encryption(PPKE) in C++ or C?

I am trying to learn how it works and eventually use Crypto++ to create my own encryptions using public private keys. Maybe theres a Crypto++ PPKE tutorial?

Maybe someone can explain the relationship(if any) between the public and private keys? Could anyone suggest some very simple public and private key values I could use(like 'char*32','char/32') to create my simple PPKE program to understand the concept?