Affirmative form:

  regular verbs:-ed is added to the infinitive: worked. If the infinitive ends in e, you only add -d: lived

  irregular verbs: you have to learn the list of irregular verbs: bought,  went, etc.

  Negative form (... auxiliary verb + not...):

you need the auxiliary do in the past tense followed by the main verb in infinitive without to:

He did not go out yesterday.

  Interrogative form (... auxiliary verb + subject ...):

You need the auxiliary do in the past + subject + infinitive without to:

Did you go to the cinema yesterday?

  when you refer to an action which happened at a particular time in the past:

Neil Armstrong landed on the moon in 1969.

  when you want to know when an action in the past happened:

  When did you see Loraine?

  sometimes the time is not mentioned but from the context it is clear that the action happened in the past.

You live in Madrid and you say to a friend: I bought this car in Paris.

  You are no longer in Paris. Your stay in Paris started in the past and finished in the past, therefore you have to use the simple past tense to talk about what you bought there.