How do you form the passé composé?

In French, the passé composé consists of two parts: an auxiliary verb and a past participle. The most commonly used auxiliary is 'avoir' (to have), although there are a few exceptions that use 'être' (to be) that must be learned, and which we will run through in a moment. First, we'll focus on the most common occurrence: using 'avoir'. If you wanted to say 'I ate' in French, we first need our auxiliary. This is very easy. We just conjugate 'avoir' as if we want to say 'I have', giving us j'ai. Now, we have to form our past participle. This is also very simple: our verb, 'to eat' is manger, ending in -er. All you need to do to create the past participle here is to remove the -r and add an accent onto the final -e to create mangé. That's it - we have our past participle. All together, we have j'ai mangé 'I ate'. However, not all verbs in French end in -er. For verbs like finir or répondre, these verbs that end in either -ir or -re, the process is still very similar: we perform the same process to the auxiliary 'avoir' (in other words, we conjugate it). However, for -ir verbs like finir all that is different is that we simply remove the final -r so we're left with fini, forming j'ai fini 'I finished'. For -re verbs like répondre, we form these by removing -re from the end and replacing it with -u to get répondu, and the final form being j'ai répondu 'I replied'. Of course, there are exceptions, but these can be learned along the way.On the other hand, the most common occurrence where 'être' is used as the auxiliary is to say 'I went', which is the irregular je suis allé(e). Notice how it is formed by conjugating 'être' exactly like we did with 'avoir': 'I am' being je suis. Then we have the past participle of aller 'to go' formed like any other -er verb: by removing the -r and adding an accent onto the final -e. The verbs that use 'être' are much fewer in number and must be learned, although they are usually verbs of movement, such as aller 'to go' and sortir 'to go out'.