FOSS gamedev and creative worlds

ok i am a noob just trying to get in
i wanted to know to to sign up for server for getting into one
honestly i dont realy know how minetest wor i know how to put in a game and mods but
not getting to multiplayer pls help :(

First find a server, you can see a list of all (public) servers here: http://servers.minetest.ru/

Then just enter with any username and password. For example this:
http://gyazo.com/2a76ac736419b85effeeaece9a2bfffa

Hope that helps.