example: I do not have many friends. ( opposite to " I have many friends") I do not have money, I do not have a car. example: I have not seen my friend in a long time. I have not taken a shower yet. I have not eaten the cake you made.

Here's a general rule: If you are using 'have' in the sense of 'tener' in Spanish, it conjugates like an ordinary verb: Do you have a pen? Yes, no I don't have one. If you are using 'have' in the sense of 'haber' in Spanish, it conjugates like an auxiliary verb: Have you read that book? No, I haven't read it. That's quite simple, isn't it? I hope it helps.

Off the top of my head, "do not have" is used for possession, and "have not" is used mostly in forming the perfect tenses. Think of "do not have" as "no tener" in Spanish and "have not" as "no haber". It might be a little more complicated to that, but that sums it up pretty well, I think. I don't have the money. - No tengo el dinero. I haven't had the money. - No he tenido el dinero.

I do not have someting. I have not do something or stuff. (I have not finished my homework.)

Thank you all for the answers. Now it is more clear.