Wann soll das Plusquamperfekt benutzt werden, und wann kann stattdessen das Perfekt benutzt werden?

The Plusquamperfekt is used to refer to the so-called "Vorvergangenheit" or pre-past, meaning that, if you are for example telling a story that is set in the past, you would be using the Perfekt tense to state what happened yesterday, but you would use Plusquamperfekt to explain what happened two days ago. Thus, the combination of the two past tenses can help clarify the order in which past events occurred.Consider an example: "Ich bin heute beim Sportverein gewesen, da mein Trainer das Training vorgestern abgesagt hatte. " Here I am explaining that I have gone to the gym today, because my trainer had cancelled the training session the day before yesterday. Let me know if you need any clarification on when to use each of the German past tenses appropriately, this may avoid confusion on how to use them correctly in the future.