Question : Understanding encryption algorithms

I need to understand how an encryption algorithm makes cyphertext and a key from plaintext.

I have tried to find examples on Google but only find things like caesar cypher (no key as such) - I need to find an example that walks through the whole process of plaintext being encrypted into cyphertext and a key.

Please could someone point me to an example or give their own.

Answer : Understanding encryption algorithms

Wikipedia has a bunch of links on this page: http://en.wikipedia.org/wiki/Encryption .  Encoding and encryption covers a lot of different methods from character substitution to dictionary encoding to mathematical algorithms.  The Cipher page tells more about methods: http://en.wikipedia.org/wiki/Cipher