How do you use the 'pluscuamperfecto' and how is it formed?

The 'pluscuamperfecto' is equivalent to the pluperfect in English, here's an example:Ya había comido la cena cuando Juán me llamó.I had already eaten dinner when Juan rang me.So we can see that the pluscuamperfecto is used to describe an action that happened one step further in the past than another. (Have a look at the timeline to understand it if you're stuck!)In terms of forming it, it's really simple, conjugate haber in the imperfect tense, and add the past participle:HabíaHabíasHabíaHabíamos + Past Participle (-ido/-ado)HabíaisHabían