The past simple is used to talk about a completed action.
Eg. I lived in Africa.

The past continuous is used to talk about an action that happened in the past but is still happening at the moment of speaking.
Eg. He was watching TV.

The past perfect is used to talk about a past action. When we talk about a past action with the past perfect, we refer back to something that happened before.
Eg. When I woke up the film had already finished.

The past perfect continuous is used to talk about an event that strated in the past and continued up until another point in the past. It is formed by had been + past participle.

Eg. He had been working in Germanu.