Here ya go, Anna:

They are both correct and in the imperative. Negative t commands are different than positive.

Cantar = to sing

present: canto, cantas, canta, cantamos, cantan
subjunctive: cante, cantes, cante, cantemos, canten
commands: t: canta; Usted (Ud.): cante
neg. commands: t: no cantes; Ud.: no cante

Yes, it's confusing! Plus, there are irregular verbs and all the usual nonsense, but in regular verbs it's just the negative t that is different.