Copy campaign into an automated series

Under CAMPAIGNS I have a welcome letter that I would like to use as an autoresponder welcome letter triggered when the lightbox subscription form (on my WIX website) is submitted.  The articles I have read step-by-step to set up a series all start with CREATE a welcome letter then select automation. My question - is there a way to COPY an alreadt created campaign and use for the automated welcome letter?  Please advise.