The imperative is used for orders, invitations and directions and is only used in the Present (direct speech). You use the base form of the verb withouth subject:
e.g.
Go away! [Vattene!/ Andatevene!]

Be quiet! [Stai zitto!/ State zitti!] .

It can be used for advice:
e.g.
Drive carefully! [Guidi/guidate con cura!]