(1) No question is "silly." You have asked an excellent question.
(2) It all depends on how you use "however."
(3) For example, no comma is needed in:
Wow! However did you learn English so fast?!
(4) But I suspect that you mean after a semicolon. Am I right?
Martha is very intelligent; however, she doesn't like to study hard.
(a) the people who write books tell us that, yes, you definitely "must" use a common after a "however" when it follows a semicolon.
(i) Some books explain that the pause is necessary because "however" in that sentence = "but."
(a) Martha is very intelligent, but she doesn't like to study hard.
(i) Did you notice how you paused after "intelligent"?