How would you command someone not to speak (hablar), using the tú command?
how would you command someone not to breathe (respirar), using the tú command?
how would you command someone not to read (leer), using the tú command?

In order to command someone to do something (or in this case, not to do something), you need to use the imperative form of a verb. In Spanish, the affirmative and the negative form of imperatives are different, and you need to learn the rules as to how to form them. However, here are my answers: 1. No hables! = Don't speak! You have the verb hablar, and when you conjugate it into its imperative form, it will be no hables. 2. No respires! = Don't breathe! 3. No leas! = Don't read!

Pay attention in class and you would know