[subject] + used to + [base verb]
[subject] + didn't use to + [base verb]
Did + [subject] + use to + [base verb]?
Used to talks about the past: things you did again and again, or things that were true for a long time, but aren't now. It's the same for every person, and the verb after it is in its base form.
Used to sounds like "yoost to", with an s sound.
With did, write use to, without the d.
For one action at one time, use the past simple. Used to is for habits and states that went on for a long time.
Used to has no present form. For a habit now, use the present simple, often with usually.
Be used to means something else: I'm used to the rain means the rain is normal for me now.