THE SIMPLE PAST TENSE

FORM:
[VERB+ed] or irregular verbs

Examples:
You called Daphne.
Did you call Daphne?
You did not call Daphne.

Completed Action in the Past
Use the Simple Past 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 they do have one specific time in mind.
Examples:
I saw a movie yesterday.
I didn't see a play yesterday.
Last year, I travelled to Australia.
Last year, I didn't travel to Canada.
Did you have dinner last night?

A Series of Completed Actions
We use the Simple Past to list a series of completed actions in the past. These actions happen 1st, 2nd, 3rd, 4th, and so on.
Examples:
I finished work, walked to the beach, and found a nice place to swim.
He arrived from the airport at 8:00, checked into the hotel at 9:00, and met the others at 10:00.

Duration in the Past
The Simple Past can be used 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.
Examples:
I lived in Bintulu for two years.
Sarah studied Japanese for five years.
They sat at the beach all day.
They did not stay at the party the entire time.

Habits in the Past
The Simple Past can also be used 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.
Examples:
I studied French when I was a child.
He played the violin.
He didn't play the piano.


IMPORTANT!
Clauses are groups of words which have meaning but are often not complete sentences. Some clauses begin with the word "when" such as "when I dropped my pen..." or "when class began..." These clauses are called when-clauses, and they are very important. The examples below contain when-clauses.

Examples:
When I paid her one dollar, she answered my question.
She answered my question when I paid her one dollar.

When-clauses are important because they always happen first when both clauses are in the Simple Past. Both of the examples above mean the same thing: first, I paid her one dollar, and then, she answered my question. It is not important whether "when I paid her one dollar" is at the beginning of the sentence or at the end of the sentence.

However, the example below has a different meaning. First, she answered my question, and then, I paid her one dollar.
Example:
I paid her one dollar when she answered my question.


Source : http://www.englishpage.com/verbpage/simplepast.html