Well I am no flowchart expert, I draw things that work for me that sorta kinda a little bit adhere to some conventions and standards.
But. In no way is your flowchart "completely wrong".
The labels in the trapezoid shapes are not usually shown as blocks in a flowchart. I do not know the proper way to add labels to a flowchart that are meant to be a guide to the source code. I'd just delete the trapezoid blocks.
There are a few stray "oui"s: blocks that do not have multiple output lines don't need "oui" or "non" on the single output - that's the path that is going to get taken no matter.
Outside of getting really picky, which would be wrong of a teacher who didn't actually try to teach you how to make a flowchart, I don't see anything wrong.
Your flowchart describes all the code and the steps that make it up.
I would love to see the flowchart the teacher expects you to have drawn…
Get the teacher to show you, or direct you to where s/he thinks it might be a good idea for you to waste spend time learning.
Google "basic flowcharting" or similar, pick some plausible website and learn someone's idea of how a flowchart should look. I don't think you are that far off.
I'm neither an expert nor a huge fan of flowcharts for program development. Diagrams have their place. For logic and code structure, I usually "sketch" my programs not yet written in so-called pseudo code, viz:
HTH
a7