You don't have to do anything until you are served with the documents. Then, you will need to file an answer within the time stated on the summons.  The answer needs to be filed with the court and a copy served on your ex by mail.If the process server left the documents with another member of your household because you weren't home, the process server will do a substituted service and mail a copy to you.  This is valid service of process and you will then have to file a timely answer as discussed above.If the process server did not leave any documents with a household member and do a substituted service, you don't have to do anything until you are validly served with the documents.