1. INDIRECT QUESTIONS
To make a question more polite we often begin with Could you tell me…? Or Do you know….?
The word order changes to subject + verb.
Compare:
Where is the post office? (direct question)
Could you tell me where the post office is?

2. INDIRECT QUESTIONS
If the question begins with an auxiliary verb, add if or whether after Could you tell me…..? Do you know….?
Compare:
Does this train go to Venice? (direct question)
Could you tell me if this train goes to Venice?

3. Reported Questions
The same changes in word order happen in reported questions.
Compare:
The police officer said to us, “Where are you going?”
The police officer asked us where we were going.
In reported speech the verb usually changes to the past.