Past simple is used principally to describe events in the past, although it also has some other uses.
To express the idea that an action started and finished at a specific time in the past. Sometimes, the speaker may not actually mention the specific time, but he/she does have one specific time in mind.I saw a movie yesterday.
I didn't see a play yesterday.
Last year, I travelled to UK.
To list a series of completed actions in the past. These actions happen 1st, 2nd, 3rd, 4th, and so on.He arrived from the airport at 8:00, checked into the hotel at 9:00, and met the others at 10:00.
Did you add flour, pour in the milk, and then add the eggs?
With a duration which starts and stops in the past. A duration is a longer action often indicated by expressions such as: 'for two years', 'for five minutes', 'all day', 'all year', etc.I lived in Brazil for two years.
Shauna studied Japanese for five years.
They sat at the beach all day.
They did not stay at the party the entire time.
To describe a habit which stopped in the past. It can have the same meaning as 'used to'. To make it clear that we are talking about a habit, we often add expressions such as: 'always', 'often', 'usually', 'never', 'when I was a child', 'when I was younger', etc.I studied French when I was a child.
He played the violin.
He didn't play the piano.
To describe past facts or generalizations which are no longer true. She was shy as a child, but now she is very outgoing.
He didn't like tomatoes before.
I waited.I did not wait.Did I wait?
You waited.You did not wait.Did you wait?
We waited.We did not wait.Did we wait?
They waited.They did not wait.Did they wait?
He waited.He did not wait.Did he wait?
She waited.She did not wait.Did she wait?
It waited.It did not wait.Did it wait?
Some signal words which will help you understand that you need to use past simple:

'ago', 'in 2011', 'in 1999', 'last month', 'last week', 'last year', 'yesterday', etc.

There are some structures which will help you use past simple accurately:
PositiveSubject + verb (-ed) / irregular verb
I jumped.

I broke my leg.
Subject + did + not + bare infinitive
Subject + was/were + not
She did not come here yesterday.
She was not here yesterday.
Did + subject + bare infinitive
Was/were + subject
Question word + did + subject + verb
Did I learn English last week?
Was she here yesterday?
What did you do yesterday?