Determine the user answer is correct, with fine-tuning

I am try to let GPT determine if a user has correctly answered a question. For example:
Question: What is the color of McDonald?
Answer: Yellow
Is Correct: Yes

And some question is related to the information that GPT don’t know. For example:
Question: What is the color of ABCD company?
Answer: Blue
Is Correct: Yes

I read the OpenAI document about completion and fine-tuning, but still no idea how to achieve it. Can someone give me some direction?

Fine-Tuning is essential a method by which you can teach GPT to answer questions in a certain way or provide it with additional knowledge that it might be missing. OpenAI API should give you a good idea on how to fine tune a model.

Completions is simply a name for the endpoint API call which you make to GPT.