In this post we are going to work on the passive voice in past simple tense. The structure is as follows:
Subject + (was, were) + vb. ppio (-ed/ 3rd C) + Agent Comp.
He opened the door
The door was opened by him
Take into account that the direct object in the active sentence becomes the subject in the passive one. The subject in the active sentence becomes the agent complement in the passive one.
Here you have some links to practise the passive voice in the past simple tense. Good luck.