When and how do I use 'etre' in the perfect tense?

The verb 'être' is used to form the perfect tense of some specific verbs. These verbs can be remembered using the acronym MRS VANDERTRAMP: Monter --> Monté Retourner --> Retourné Sortir --> Sorti Venir --> Venu Aller --> Allé Naître --> Né Descendre --> Descendu Entrer --> Entré Rentrer --> Rentré Tomber --> Tombé Retourner --> Retourné Arriver --> Arrivé Mourir --> Mort Partir --> Parti
The conjugation structure goes: Person + 'être' + past participle of verb eg: Je suis arrivé (I arrived)eg: Tu es parti (you left)
Important: Because the verb 'être' is being used, the past participle of the verb needs to agree with the person doing the verb.Example: Nous sommes arrivés (the plural past participle agrees with the plural 'nous')eg: elle est rentrée (the feminine past participle agrees with the feminine 'elle')eg: elles sont descendues (the feminine and plural past participle agrees with the feminine and plural 'elles')