Bienvenuta, if that's how you say welcome in italian =P!
TimeKeeper explained most everything.
However, you do not have necessarilly to create a town to be officially one. You can be apart of a "wilderness town", a town that isn't using the towny plugin. Since your stuff is already protected in the wilderness due to the rules, and since you are all friends with eachother, this seems to be a better option. With this option, you do not need to worry about griefers. You just have to call a staff member when an unexplainable grief happens.
If you are planning on adding new players to your town that you don't know personally, then creating a town with the towny plugin is the best option! I suggest when creating the town, you place some money on the bank (around 1000$) because the town upkeep might make your town bankrupt and fall into ruins. The nation is optional, you cannot be forced to join one if you do not want to. If you need any help with towny commands in the future, you can always check the /tutorial, ask help online and/or on the forums, some members are always willing to help!
