How do I form the pluperfect?

First, let's understand when to use the pluperfect. The pluperfect is a tense expressing a past action, which is before another past action. For instance, "J'allais a la piscine car j'avais fini le dîner".  Here, it is used to express the fact that I went to the swimming pool, past action, because I had finished dinner, which is also a past action but preceding it. The second action used with the pluperfect is usually conjugated with the imparfait, passé composé or passé simple. Is this example, "allais" is imparfait, "avais fini" is the pluperfect.  It's formed in two parts: "avais", the auxiliaire, which is here the auxiliaire avoir but can usually be etre or avoir. It is conjugated with the imparfait. The second part is the past participate. The past participate is only modified with the feminin/plural subject with the "etre" auxiliaire, not with the "avoir".  For instance, you will write "Elles allaient a la piscine car elles avaient fini de diner", where "fini" is not modified as the auxiliaire used is "avoir" (however as you can see, the imparfait of the first action and of the pluperfect are conjugated).  If using the auxiliaire "etre", you will say "Elles allaient a la piscine car elles etaient prêtes a partir". Here, the verb "prêtes" is therefore modified to a feminin plural form.  Do you have any other questions? Would you like me to give more examples?