It really depends. If you are talking about a specific detail that happened in the past, or an activity you used to do continuously in the past, you use imparfait or to describe a singular event that happened (Last year, last week, last Sunday etc.) you use passe compose avec avoir or etre as your auxiliary verbs.
The following are the verb endings for imparfait -
-ais, ais, ait, ait, ions, iez, aient
To form the passe compose avec avoir/etre you have the pronoun (je, tu, il, elle, nous, vous, ils, elles) followed by the auxiliary present tense of avoir/etre and the past participle.
The first one is elle a fini les devoir
the second is il parle anglais ici
These are all in present tense
Avoir - to have
J’ai - i have
Tu as - you have
Il/elle/on a -he/she has
Nous avons -we have
Vous avez -you (plural) have
Ils/elles ont - they have
Être- to be
Je suis- i am
Tu es- you are
Il/elle/on est- he/she/it is
Nous sommes- we are
Vous êtes- you (plural) are
Ils/elles sont- they are
Aller- to go
Je vais- i go
Tu vas- you go
Il/elle/on va- he/she/it goes
Nous allons- we go
Vous allez- you (plural) go
Ils/elles vont- they go
