I presume that you are asking about the difference between the past simple and present perfect tenses. Did you see that movie? = Past simple Have you seen that movie? = Present perfect You use the past simple with expressions about past time - last week, yesterday, ten years ago, in 2005, when I was a child. All of these time periods are finished. You use the present perfect with unfinished periods of time eg since 2005. For example: Have you ever studied English before? No, I haven't. It's my first time. = in your life up to now How long have you been a teacher? I've been a teacher for 20 years = from when you began until now The important thing to remember about the present perfect tense (Have been/have done etc) is that it tells you something about the present time, such as the fact that this is the first time that you have studied English, or that the person is an experienced teacher. I hope that's clear. Please ask if there's anything else you need to know.

"Have" is used to say that you have the experience of doing something. For example, A: Have you ever been to that place? B: Yes, I *have* been there. (experience) "Did' is used to emphasis the fact that you did something. For example, A: Did you bring the things I asked you to? B: I *did* bring them. (emphasis)