"Do not be afraid."
Translation:No tengas miedo.
To Iago -- not sure what "it" you are referring to about being different.
Tu' commands : the "yes, do it" commands are in their own little universe ( haz, di, ten, ven, etc.) but the negative tu' commands look just like tu' subjunctive (no digas eso, no hagas la cama, etc.) Hope that helps....