The easiest way to make a sentence negative in Spanish is to put no in front of the verb. For example:
No me gusta el libro (I don't like the book).
No fuimos al cine (We didn't go to the cinema).
No es moderno (It's not modern).
When answering a question, no is often repeated for emphasis, eg No, no tengo hermanos (No, I don't have any brothers or sisters).
No must go after the subject and before the verb, eg Mi hermano no es alto (My brother is not tall), Los j贸venes no estan contentos (The young people are not happy).
Never separate direct or indirect object pronouns from the verb. Simply place the negative word in front of the pronoun, eg no lo conozco (I don't know him), no lo he visto (I haven't seen it).
Some other useful phrases with no are:
Ya no (no longer, not anymore), eg Ana ya no vive aqu铆 (Ana doesn't live here anymore).
Todav铆a no (not yet), eg todav铆a no he hecho mis deberes (I haven't done my homework yet).