To my mind you learn the difference little by little. Unfortunately it is difficult to apply rules consistently such that you would know in every case which is right. You will get a "feel" for them over time by encountering them in different situations. Don't worry too much about it, just notice them when you see them - that's my advice.

The simple past is for actions completed in the past. It is a good first choice, if you are not sure. It is used much more than other past tenses. "I finished my lesson". The present perfect is for actions which were completed in the past but which have a relevance right now, in the present. "I have finished now. Could you check it for me?" I hope this helps. These links may also be useful. https://www.ef.co.uk/english-resources/english-grammar/simple-past-tense/ https://www.ef.co.uk/english-resources/english-grammar/present-perfect/ https://ginsengenglish.com/blog/english-verb-tense-frequency

pluperfect aka past perfect is used for something competed, but relative to a point in the past, rather than the present. https://www.espressoenglish.net/difference-between-present-perfect-and-past-perfect-in-english/#:~:text=Both%20present%20perfect%20and%20past,point%20is%20in%20the%20past. says Both present perfect and past perfect talk about something that happened before a point in time (reference point). In the present perfect, our reference point is the present. In the past perfect, our reference point is in the past. Present Perfect An action that started in the past and continues to the present. I have lived in this city for six months. An action that happened before now (unspecified time) I have been to Japan twice. HOW TO FORM THE PRESENT PERFECT: HAVE / HAS + past participle EXAMPLES OF THE PRESENT PERFECT: My mother has just gone to the store. Janet has lived abroad for five years. I haven’t seen the new movie yet. Have you finished your homework? It’s very common to use the contractions ‘ve and ‘s in the present perfect: I’ve been to Japan three times. My mother’s just gone to the store. Janet’s lived abroad for five years. Past Perfect An action that happened before a time in the past When I arrived at the office this morning, I discovered that I had left my computer on the night before.