Help for beginner

Hi, I’ve just recently started a production class at school and have begun working on an assignment. I did a few things wrong and my professor told me I would need to “re-record“ something to get the levels correct but it was something I pulled from online and he knows that since it was a song clip. How can I record this? What does he mean? I had already asked him too many questions and asked for too much help. I didn’t want to be a bother. Thank you.