With the imperative, the reflexive pronoun is attached to the end of the conjugated verb
E.g
Alzati presto! - Get yourself up early!
Siediti qui! - Sit yourself down here!

In the negative form, the reflexive pronoun can either come before the infinitive or attached to the end if the infinitive, with the final -e of the infinite dropped.
E.g
Non ti alzare presto! or Non alzarti presto!
Don't get yourself up early!

Reflexives in the Imperative