Remember that the present perfect is the present tense and the past simple is the past tense.
If we are talking about some period of time that began and ended in the past (yesterday, last week, two years ago, last summer), we use the past simple.
If the result of the action has to do with the present moment and there are no words like yesterday, a week ago, last month, we use the present perfect.
What did you do yesterday? (yesterday = in the past)
What have you done? (= now)
I read a lot when I was a teenager. (when I was a teenager = in the past)
I haven't read this article yet. (up to now, but I still can read it)
Bob called me two days ago. (two days ago = in the past)
Don't email Alex, I have already called him. (no indication of the finished time, the result is important for the present moment)
We were in Turkey last summer. (last summer = in the past)
We've been to Turkey twice. (up to now, we can still go there again)
This table of the signal words will help you choose between the present perfect and the past simple:
last (last Sunday, last month, last year…)
ago (five days ago, a week ago)
when (when I was a child)
in + year
on + date
(in 1988, in June, on Monday, on April 26)