되다 is one of major Korean verbs. There is no such word of 되어다. Maybe it might be mistaken as the past tense of 되다, '되었다'. 되다 which has many meanings is basically used for meaning 'be' or 'become'. For example, 나는 여배우가 되고 싶어요. (I want to become an actress). Or it has a meaning of state change like 공부가 잘되다 (My studying goes well) 오래된 자동차 (The old car)..