Some questions ask for more information than a simple sí or no. For these, you'll need to begin with a question word.
¿Quién habla francés?
Who speaks French?
¿Qué día es hoy?
What day is today?
¿Dónde vive ella?
Where does she live?
¿Cuándo es el partido?
When is the match?
¿Cómo estás tú?
How are you?
Let's talk more about stress! When there is no accent mark and a word ends in a vowel, n, or s, the second-to-last syllable receives the most emphasis.
But! If there is no accent mark and a word ends in a consonant (other than n or s), the last syllable is stressed.