Using HAD, HAVE and HAS

When do we use the words HAD, HAVE and HAS in sentences?

Ola's answer:

I, you, we, they => HAVE (present tense)

I, you, we, they => HAD (past tense)

He, she, it => HAS (present tense)


Example sentences:

- We have cookies. Would you like some?

- We had cookies, but we ate them all.

- She has cookies. Ask her if you want some.