The past continuous is very simple if you know the present continuous. Just change the verb "to be" into the past:

I am watching TV now I was watching TV yesterday
She's not listening to me! She wasn't listening to me!
are you playing golf with Susan? Were you playing golf with Susan last Monday?

SIMPLE PAST VS PAST CONTINUOUS

We use the simple past to say that something happened at a particular moment:
- I worked 5 hours yesterday
- I lived in Rome when I was a child

We use the past continuous to say that something was happening at a particular moment: the action started before that time, and it finished at that time:
- Yesterday, at 3 o'clock, I was working
- In 1980 I was living in Rome (I went to Rome before 1980 and I also lived in Rome after 1980)
- In 1980 I lived in Rome (I went to Rome in 1980, I lived there for one year but in 1981 I was living in a different city)

When we use the simple past or the past continuous, I am talking about a past action, not a present one, so if I am still living in Rome I can't say "I was living in Rome", I have to say "I am living in Rome".

The most common use of the past continuous is when telling a story. We use the past continuous to describe an action that was happening for some time and then stopped when another action happened. Look at this: Past Continuous.

Here you can practise with these exercises (at the end there is a button to check your answers) :
Exercise 1, Exercise 2.