This teacher will explain the verb TO HAVE in the present and in the past.

PRESENT

I have - I don't have
You have - You don't have
He/she has - He/She doesn't have
We have - We don't have
You have - You don't have
They have - They don't have

PAST

I had - I didn't have
You had - You didn't have
He/She had - He/She didn't have
We had - We didn't have
You had - You didn't have
They had - They didn't have

HAVE = HAVE GOT = GOT

HAVE is more normal in American English and written British English
HAVE GOT is more normal in conversational British English
GOT is only used in colloquial English, especially in America

HAVE (normal verb, uses "do")
Affirmative

I have a pen
You have a pen
She has a pen, He has a pen, It has a pen
We / You / They have a pen

Negative

I do not have a pen = I don't have a pen
You do not have a pen = You don't have a pen
He does not have a pen = He doesn't have a pen
We / You / They do not have a pen = We / You / They don't have a pen

Questions

Do I have a pen?
Do you have a pen?
Does he/she/it have a pen?
Do we/you/they have a pen?

HAVE GOT (special verb, doesn't need "do" / only British English)

I have got a pen = I've got a pen
he has got a pen = he's got a pen

I have not got a pen = I haven't got a pen
He has not got a pen = he hasn't got a pen

Have you got a pen?
Has he got a pen?

GOT (colloquial, especially America)

I got a pen
you/we/they got a pen
he's got a pen

negative:
I haven't got a pen / I ain't got a pen
he hasn't got a pen / he ain't got a pen, etc.
(ain´t is the colloquial AmE form for the negative of "to be" or "to have")

question:
you got a pen? / he got a pen?