Dragon Japanese

How do you say ‘A boy who becomes a dragon’ in Japanese?

I wrote －のおとこのこのひとひりゅうになります。 in my paper, and she didn’t say anything about that?
Could this be right?

I don’t think that’s right. This is better:

竜に成った男の子

りゅうになったおとこのこ

Japanese Dragon Painter