English uses verbs in the simple past tense to refer to actions situations, or events that are finished and that happened before now. Here are the more detailed explanation about the simple past tense uses.

The simple past indicates that an activity or situation began and ended at a particular time in the past

I walked to school yesterday.
He lived in Paris for ten years, but now he is living in Rome
I bought a new car three days ago

If a sentence contains when and has the simple past in both clauses, the action in the “when clause” happens first.

I stood under a tree when it began to rain.
When she heard a strange noise, she got up to investigate.
When I dropped my cup, the coffee spilled on my lap.

How do we make the Simple Past Tense?

To make the simple past tense, we use:

past form only
or
auxiliary did + base form

Here you can see examples of the past form and base form for irregular verbs and regular verbs:

	V1 base	V2 past	V3 past participle
regular verb	work explode like	worked exploded liked	worked exploded liked	The past form for all regular verbs ends in -ed.
irregular verb	go see sing	went saw sang	gone seen sung	The past form for irregular verbs is variable. You need to learn it by heart.
			You do not need the past participle form to make the simple past tense. It is shown here for completeness only.

The structure for positive sentences in the simple past tense is:

subject	+	main verb
		past

The structure for negative sentences in the simple past tense is:

subject	+	auxiliary verb	+	not	+	main verb
		did				base

The structure for question sentences in the simple past tense is:

base

+	subject	+	main verb
did				base

The auxiliary verb did is not conjugated. It is the same for all persons (I did, you did, he did etc). And the base form and past form do not change. Look at these examples with the main verbs go and work:

	subject	auxiliary verb		main verb
+	I			went	to school.
+	You			worked	very hard.
-	She	did	not	go	with me.
-	We	did	not	work	yesterday.
?	Did	you		go	to London?
?	Did	they		work	at home?

Exception! The verb to be is different. We conjugate the verb to be (I was, you were, he/she/it was, we were, they were); and we do not use an auxiliary for negative and question sentences. To make a question, we exchange the subject and verb. Look at these examples:

	subject	main verb
+	I, he/she/it	was		here.
+	You, we, they	were		in France.
-	I, he/she/it	was	not	in Jakarta.
-	You, we, they	were	not	happy.
?	Was	I, he/she/it		right?
?	Were	you, we, they		late?

Note: For the negative and interrogative simple past form of "do" as an ordinary verb, use the auxiliary "do", e.g. We didn't do our homework last night. The negative of "have" in the simple past is usually formed using the auxiliary "do", but sometimes by simply adding not or the contraction "n't".
The interrogative form of "have" in the simple past normally uses the auxiliary "do".