Good evening ^^ I am very confused by this sentence in Harry Potter, can someone explain it to me? 新聞 の 上 を 歩く んだ よ Thanks in advance ♡

Good evening ^^ I am very confused by this sentence in Harry Potter, can someone explain it to me?
新聞 の 上 を 歩く んだ よ

Thanks in advance :heart:

Aunt Petunia is telling him to walk on the newspaper.

〜んだ=〜のだ (command form)

Thank you very much for your reply!
Are you familiar with the story and happen to know what she means by this? I could understand the direct translation, however it seems a bit strange in the context it is written in, so I was wondering if the actual meaning might be something else?

Yeah, I know the story. I think she’s asking him to walk on the newspaper so he doesn’t get the floors dirty.

I see, haha! Thank you very much :heart: