1
Could you tell me when does the course start?
Could you tell me when the course starts?
Do you know where is the school?
Do you know where the school is?
In indirect questions beginning with expressions such as Could you tell me…? or Do you know…?, use normal sentence order after the question word: subject + verb.
Compare: ‘What is the time?’ and ‘Could you tell me what the time is?’
2
I don’t know how much does it cost.
I don’t know how much it costs.
I’d like to know where were they going.
I’d like to know where they were going.
Use the same word order after expressions such as I don’t know, I’d like to know and I wonder.
Do not put an auxiliary verb before the subject and do not add do/does/did: how much it costs, not how much does it cost.