Some verbs can be followed by a question word + clause. Study the following sentences.

I asked what she was doing.
Nobody knows how he did it.
I wonder why she is angry with me.
She showed how annoyed she was.
I can’t decide what I should do next.
I don’t understand why she has behaved like that.
He couldn’t figure out what he should do.

The important verbs used in this pattern are: say, ask, wonder, know, believe, imagine, decide, discuss, understand, show, reveal, suggest and tell.

Some verbs can be followed by a noun / pronoun + question word + clause.

She asked me why I was angry with her.
Tell me what this is.
I showed them how they should do it.
Could you please tell me what I should do?
Can you tell me where she lives?

Verbs that can be followed by an object + interrogative are: tell, ask, show, teach, advice and inform.

Grammar notes

In the question word clause we use normal word order: subject + verb.

Tell me who she is. (NOT Tell me who is she?)
Could you please tell me what I should do now? (NOT Could you please tell me what should I do now?)