Is nouvelle the feminine form of nouveau?
when does the adjective go before or after a noun?
why is "nous" as we wrong?
Nous is correct Emil: "Nous écrivons une nouvelle lettre." Perhaps you had a mistake somewhere else?
Ah I wrote nous écrit.. so it's either "on écrit" or "nous écrivons"
That sounds about right. Next time make your question more detailed (like, copying your whole answer) and you'll make it easier to help you. ;)