Scratch

I'm trying to create a project using mesh, however I have very little understanding of it. I've searched the  forums for some kind of guide, but I could find nothing. from comments left on other peoples questions (please correct me if I'm wrong) I've learned:

Mesh works by sending broadcasts to every program connected to your network.
Mesh can only connect people on a local network by itself.
Using a program called Hamachi, you can allow mesh to connect over the internet.

I really want to know if this is all there is to mesh, it seems to simple and I fell like I'm missing something really important.
Also, how do you set up Hamachi, I have the program and my computer just registers it as it's own network, is it supposed to do that?