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.