There are 16 verbs in French that require être rather than avoir in the passé compose. Sometimes there is a passé. Passé uses être to talk about physically passing by something. These irregular verbs also must agree in gender and in number.
There are 3 kinds of regular verbs in French: -ER, -IR, -RE. Once you’ve learned the rules of conjugation for each of theses three kinds of verbs, you should be able to conjugate regular verbs in each of those categories with ease.