How to answer this question? Yes or No

Sorry, if this question is naive.

If someone asks me,

"You didn't go to school today, right?"

If I did not, should I answer, Yes or No?

Similarly,

"You do not like eating fish, do you?"

If I do not like eating fish, should I say Yes or No?

Answer

No, I didn't go to school.
Yes, I went to school today.
You are right, I didn't.