I'm also a first time VPS admin and have just had this same confusion today (hence my search which turned up this thread).
I've since found out that Netenberg is actually the name of the company that makes Fantastico, i.e. they are asking where would you like a folder called "netenberg" to be created for Fantastico to be installed into. I chose /var so it installed Fantastico in /var/netenberg on my VPS.