When it is used
In oral or written speech when you talk about something finished, something that only happened once, something limited and precise
English equivalent - Past Simple and Present Perfect
Tense determiners: hier, autrefois, auparavant, il y a, etc.
How it is formed
The construction of the past tense is the following
avoir/être + verb in past participle
Group 2 - ir becomes i
j'ai fini
tu as fini
il a fini
nous avons fini
vous avez fini
ils ont fini