Allez, ne t'inquiete pas!!
Bon, on continue en anglais ou en francais?
Okay, so for the passive voice, you don't have to use at any specific time, per se. Like in English:
The teacher taught the lesson (active)
The lesson was taught BY the teacher (passive)
Same goes for french, you already know the way to conjugate so it shouldn't be too difficult.
right, for an example:
Les travaux bloquaient la route. (the works blocked the road) active. So, passive in English would be : the road was blocked by the works.
in french:
La route etait bloquee par les travaux.
Always note the tense used in the original.
I hope I've been somewhat coherent. Feel free to ask questions, because I don't think I'd understand much from what I wrote.
I blame it on strange french grammar.
Desole!!
Bonne chance!