Question tags are very similar to reply questions. The only difference is that the reply questions are used by the listener and the question tags by the speaker himself.
A question tag consists of an auxiliary verb and a personal pronoun.
It is used at the end of a sentence and means as much as "right?".
With a question tag you use the same auxiliary verb as in the sentence:
You're Andy's brother, aren't you?
He can sing, can't he?
If the sentence down't contain an auxiliary verb, use a form of to do:
You lost, didn't you?
Intonation plays an important role in tags. When the intonation goes down it is simply an addition to the sentence:
So she doesn't like wine, does she? (not a real question)
But when the intonation goes up it is a real question and an answer is expected:
She does like wine, doesn't she? (a real question)
If the sentence is affirmative, the tag is usually negative, and vice versa.
She likes wine, doesn't she?
She doesn't like wine, does she?
But that is not always the case. If you are questioning the information, use a similar tag.