Hi and welcome. I'm going to try my best to help, but I have no basis in my information except for what I'm reading and find on websites, so... use information at your own risk.
This is Croatia to/from Italy (ferry). Not sure exactly what your question is...
Ferry site 1
Here's another site on Croatia/Italy.
Again, haven't been to Greece yet, so I cannot vouch on behalf of any transport system.
Here's a
link to a website for some transportation.
This is the main site for tourism in Greece. I'm sure they'll have lots of great links.
Remember if the site isn't in English, to look around for a US/Brit/Can flag
.
Hope this helps a little.