I don’t see a default directory that has my domain name. Do I create one myself. Is there a www directory similar to other hosting companies?
From the “manage domains” page in the panel, look at what “user” appears for that domain in the “web hosting” column. Log into that user and you will be placed in that users home directory (i.e. /home/USER where USER is the actual user name). In that directory you should see a DOMAIN.COM directory i.e. /home/USER/DOMAIN.COM ) what’s placed in the DOMAIN.COM directory is the root of your website DOMAIN.COM.
when I login to https://webftp.dreamhost.com/. I only see 2 directories( MailDir, Logs)
Are you sure you are logging in with the correct user? It sounds like you are logging into an FTP user that is not connected to that domain (or in fact connected to any domain). Check as described above what specific user is connected to the specific domain and log in with that user.