i read that you installed snort and think you are having trouble having it run, ppalias has given you the command to start snort “service snort start” and i would imagine the command to stop it is “service snort stop”, but it appears from the log that it is running. are you expecting to see a page dedicated to snort? as it stands all you can do from the web gui is to view the log. from the posted log it appears to be running.
plz be more specific w/ what exactly is your problem, then we can better assist you.
(do you have an ssh client to access ZS, did you enable ssh in the system SSH? PuTTy is my favorite)