Have you read the Wikipedia article? It's not written for lay people but it's not bad. Using it you should be able to prove to yourself that if the key has less entropy than the message it's not possible to achieve this level of security.
https://en.wikipedia.org/wiki/Information-theoretic_security> i'm not using any traditional math
That doesn't get you an out - the theorems don't care how you transform M to C.
