Active sentences are sentences where the subject performs the action.
Passive sentences are sentences where the subject does not perform the action of the verb.
The passive voice is used to show interest in the person or object that experiences an action rather than the person or object that performs the action.
You have to change the structure, so the object in the active voice becomes the subject in the passive voice.
You have to use the verb 'to be in the same tense as the main verb in the active voice.
You have to use the past participle of the main verb.