I've noticed that this is a difficult point for Spanish students, so I'll set here the conjugation of Imperative mode in Spanish. in fact, it's quite simple, but odd, we should admit it...

When you see an Spanish ordinary conjugation, imperative mode (the one we use to give orders) is described like this:
AMAR
- yo
ama tú (ame usted)
- él/ella
amemos nosotros/as
amad vosotros/as (amen ustedes)
- ellos/as

Ok. However, when it comes the moment of a negative order, the problem arises. We use (don't ask me why, although I have my own crazy theories) a form exactly similar to the present subjunctive in second person (in fact, it was already similar to present subjunctive forms in positive in the other forms, "we", "usted" and "ustedes"). So:
- yo
no ames tú (no ame usted)
- él/ella
no amemos nosotros/as
no améis vosotros/as (no amen ustedes)
- ellos/as

Pronominal verbs (verbs with a pronoun incuded in the verb, like "levantarse") also give some difficulties.
Levántate - No te levantes / Levántese - No se levante
Levantémonos - No nos levantemos
Levantáos - No os levantéis / Levántensen - No se levanten