"누가 저녁을 준비했어?"
Translation:Who prepared dinner?
This site has helped me understand the difference between passive and active verbs; it has a section specifically on 하다 to 되다 type verbs: https://www.howtostudykorean.com/unit1/unit-1-lessons-9-16/lesson-14-korean-passive-verbs/#kpv1
I'm not sure why this program is keep missing the articles in front of the nowns.
Do you mean as in "the dinner" instead of just "dinner"? In English, this article is often omitted.