Do is used for questions without question words (EXCEPT FOR « to be », see below)

FORM
Do + Subject + Verb (present simple)
Did + Subject + Verb (past simple)

EXAMPLE 
Do they have tyres? (present simple)
Did they have tyres before ? (past simple)

REMINDER 
For the verb « to be », do is not used.

EXAMPLE 
Were you good at History ?