Are you done with answering the subquestions and did you use the feedback of the teacher to complete/adjust your answers?
Then you are ready to answer the main question.
Use at least 400 words for this. Make sure every group member works on this. This is the most important part of your research.
Use information from all the subquestions to form the answer on the main question.
You should never use new information here.
In the conclusion you first give a short summary of the answers of the subquestions and then come to a conclusion (an answer to the main question).
As soon as you formed the answer to the main question, you are ready to create your report.