Asking of meanings of some words

Hello! I'm from Uzbekistan. I'm beginner in english knowledges. therefore there can be lots of mistakes in my sentences.
Also i'm new joined member in this wonderful site. I hope i could somehow learn and improve my english speaking with u, dear forummates.

well, my question is like below:
Often when i be in forums chats etc i come across with such words like: "dude", "yeap", "c'mon", "... rock or rocks" end so on. These words as i think are used in street conversations, i mean slangs. therefore I could'nt find their meanings in dictionaries. So, What do these words mean?

It would be great, If someone does me a favoure answering my question, and showing me my mistakes in the post.

Thank you

with regards Abbas