Regular verbs add -ed (e.g. want - wanted, love - loved, shout - shouted)
Irregular verbs are numerous and varied (e.g. buy-bought, fall-fell).
Questions require did:
- When did you return to Brazil?
Did she go on holiday last year?
Negative phrases use didn’t or did not:
- They didn’t go to Rio de Janeiro last month.
- I didn’t see you last night.
- to describe actions and states that occurred during a time period that finished in the past (e.g. yesterday, last year, in 1999).
- He returned to Brazil last year.
- to describe actions that happened regularly in the past.
- We walked to school every day last week, but this week we are driving.
Note: the past simple is also used in conditional structures and phrases to sound more polite/formal (e.g. Did you want to have a meeting with me now?).