It is confusing

here are a few examples to help me spot the pattern:

I will tell you a story.
not
I will say you a story

Did you hear what I said?
and also
Did you hear what I told you?

I told you not to go there.
needs more words:
I said you'd better not go there.

"Look" he said.
but never:
"Look" he told.

It seems tht "tell" needs an object, either a person's name or a pronoun to have something "addressed" to them

"say" is used to refer to the actual words spoken ..

that's a start, anyway!