To ask where something is in Korean, you must use either the copula eo-di-yeo-yo 어디예요 or eo-di iss-eo-yo 어디있어요.

Where is it? 어디?

학교는 어디있어요? hak-kkyo-neun eo-di-iss-eo-yo? Where is the school?

To answer a where-question, you have to use iss-eo-yo as a verb:

학교가 저기 있어요 hak-kkyo-ga jeo-gi iss-eo-yo (The school is over there).