When making a question using the simple past, you will have to use did just as you learned to use do with the simple present tense.

SIMPLE PRESENT:

Statement:
--They accept credit cards.
Question:
--Do they accept credit cards?

SIMPLE PAST:

Statement:
--They accepted credit cards last year.
Question:
--Did they accept credit cards last year?

When using did in a question, the main verb will be in the infinitive form, not the simple past tense.

NOTE: For a negative question in the past, use didn"t.

--Didn"t you get my letter?

--Didn"t they come?