I watched a YouTube video about Diffie-Hellman called "Diffie-Hellman Key Exchange", and it said after doing some modulo operations with the public modulus and generator and the random private numbers, you eventually arrive at a shared secret, or key between Bob and Alice (or whoever is exchanging data). Now that you have the key, how do you use the key to encrypt and decrypt data over whatever channel you are sending over? Do you use the key as the generator? Please give a mathematical example of how to encrypt and decrypt using the key.
Typical scenario is to run the raw shared secret through a key derivation function to generate keys for any symmetric primitives they will use.