[kisito]

This is always a challenge for students but I have created these exercises that help to give practice. There are several reasons why we use the present perfect and not past simple and vice versa, but this cannot be cleared up in one lesson you need practice.
Try these:
Printable Games for present perfect vs. Past Simple
Wheel Game
There are interactive games on this page on the subject.

The most common reason for using the present perfect is to talk about actions that started in the past but have relevance to the present and may not be over in the near future. For example:
"I have lived in China for 6 years."
But if I said: "I lived in China for six years."
This suggests an end to living in China. The action has stopped in other words. But by sayig: "I have lived in China for 6 years.", I am suggesting that the action is not over.

But that is not all. Using EVER and NEVER we can form the present perfect to talk about things that may have happened in the past, but we may not be too keen on when it happened. All we are interested in knowing is whether it happened. For example: "Have you ever been to China?". ANSWER: "Yes, I have been to China several times." If I am interested in time in the past, I will use the past simple: "When did you last visit China?" ANSWER: "I visited China last year."

We also use the present perfect with words like JUST, ALREADY, YET as in these examples:
"He has just arrived."
" I have already eaten dinner."
"I haven't eaten dinner yet."

The reason why it is called PRESENT PERFECT is that the present is perfectly connected to the past and possibly the future. But to include future will be leading us to PRESENT PERFECT CONTINUOUS, which is another one.

The PAST SIMPLE is for actions that are over.

Hope this helps!