have not or don't have

[C3laudia]

I don't understand, sometimes people use "have not" or "had not", I think is don't have, or didn't have, I am confused.

[Ben777]

When we use "have not", we are trying to express that something hasn't been done yet. For example, "I have not had a shower yet, because I don't have to go to work for another 3 hours.
When we use "don't have", we are trying to express that something is not in our possession, that we do not own something. For example, "I don't have my own house because I can't afford the bills."