There are two steps that come with the Passé Composé.
The first step in forming the past tense is conjugating the helping verb. In order to complete the first step, you need to know the two helping verb choices. The two are avoir (to have) and être (to be). Lets start off with avoir first.
J'ai- i have, tu as- you have, il/elle/on a- he/she has, nous avons- we have, vous avez- y'all have, ils ont- they have
these are the avoir helping verbs.
The second step involves the past participle, it directly follows the helping verb.
étudier (to study) - étudié____finir (to finish)- fini ___entendre (to hear)- entendu
This is the past participle is used with the regular verbs
But there are many irregular past participles as well. These verbs have different endings, such as voir (to see) which would end up as vu. Another example is prendre (to take), instead of being prendu, because its irregular it would be pris.
Now onto être.
Je suis- i am, tu es- you are, il/elle/on est- he/she is, nous sommes- we are, vous êtes- y'all are, ils sont- they are
these are the être helping verb
there are two cases in which you use être. The first, is Dr. Mrs. Vandertrampp, and the other is the reflexive verbs. We will be going over Dr. Mrs. Vandertrampp, which is states of being or motion.
Dr. Mrs. Vandertrampp is an acronym for the past participles for être. For example, the d in Dr. Mrs. Vandertrampp stands for devenir(to become) which becomes devenu. Putting it in a phrase would look like this: Je suis devenu.
The biggest thing to remember with Dr. Mrs. Vandertrampp is that the past participle must agree in number and gender with subject. For example: je suis allé. If you were female, it would be: je suis allée. For feminine, you add an e, plural you add an s, and if its plural feminine you would add an es.