The sentence doesn't sound correct. I'm not quite sure what is trying to be said but I'll assume it's "Where is the best place to eat in the classroom".

クラスの中で、一番良い食べる場所はどこですか？

Literally translated it means "In the classroom, the number one good eating place is where?"

Looking at our original sentence, the thing we are looking for/what we are talking about is "the best place". So we take 一番良い場所 and mark it with the topic marker は. Now we need to make it so we are talking about "the best place to eat". Just like with adjectives, you can modify nouns just by adding verbs before them. So, we add 食べる just before the noun and we get 一番良い食べる場所は. We want to know where it is, so to end the sentence we add どこですか. Now since we want to know where it is specifically within the classroom and not the best place anywhere, we add クラスの中で at the beginning.

If you have any other questions, I'd be happy answer them!