To the end of the first word.
To the verb (so the verb being the first word of the question)
You can play with words, and if you put it on something else than a verb, or if you place the -ne-word in the middle of the sentence or elsewhere, it's not grammatically wrong. It's simply unusual (but can be found in Latin literature, -poetry or not), and it changes the emphasis of the word.
The -ne is used on the word the question is.