I'm sorry for the very dumb question, but I just can't grasp the concept of codes.
If C is an [n, k] linear code, what are n and k exactly? I know k is the dimension of C and that n is the number of tuples of the field where C is a subset of. Is n the dimension of the field? If so, why should it be specified? What does C looks like? What does its code words look like? I've read codewords are just vectors in C, and they are mainly denoted by (a1, a2, ..., an), but what are these a's? From the field?