"Var inte ledsen!"

Translation: Do not be sad!

[kounsh]

I don't understand how this can be translated as "Don't be sad". Can someone explain the "Var inte" part?

[Zmrzlina]

Var inte means, literally, be not.

[kounsh]

Isn't "var" the past of "är"? So I wasn't sure how to translate it well...

[Zmrzlina]

It's also the imperative, which is used here.