Can someone help pleaseee

Explain what has to happen when you use être instead of avoir for the formation of the passé composé? il an english explanation with steps if possible

Marion went on a trip to france and sent a postcard to her aunt brigitte describing the places that she has visited. what place did marion not go to? the beach the city the mountain the countryside

Whats the definite article for the word: examen 1- les 2-l' 3-la 4-le is élevé masculine or feminine? (could be both) whats the plural form of the word le tableau?