Oleg, your explanation is incomplete and partially incorrect. Sorry to say that

.
So let us clarify the differences between Present Perfect and Past Simple.
1.
Past Simple is used to describe actions that happend in a DEFINITE time in the past.
Example: I bought a new dress
a week ago. Present perfect is used to describe actions that are happened in an INDEFINITE time in the past.
Example: I've bought a new nail polish. (I am not telling you when exactly did I buy it).
2.
Past Simple is used to describe a past habit or a state that no longer are happening.
Example:
When I was young I lived in a village. (I am not young anymore)
Present Perfect is used to identify actions that happened in the RECENT past, so that you still can see results of these actions.
Example:
I've just painted the room. (You can still smell paint in the air).
3.
Past Simple is used to identify several actions, that happened one after another.
Example:
She put on her coat, took her bag and left the house. Present Perfect is used to identify actions that started in the past, but are still happening in the present.
Example:
I've lived here for two years. (And I still am)
However, if I no longer live there, I'd say: I lived in Kiev for two years.
4.
Past simple is used to identify past events that happened in an indefinite time in the past, and that can NO LONGER happen neither in the present, nor in the future.
Example:
I saw Gianni Versace. (I will never see him again because he passed away).
Present perfect is used to describe events that happened in an indefinite past, but that can be repeated now or in the future.
Example:
I have met Vladimir Putin. (He is still alive, so I have a chance to meet him again

).
Actually, with
Past simple you usually use such words and phrases as: yesterday, last week\month\year\Monday, ago, how long ago, just now, then, when, in 1987
With
Present Perfect you would use: just, ever, never, always, already, yet, for, since, so far, how long, recently, today, this week\month\year\Monday, once, several times.