How do I play on a multiplayer server?
Playing on a local network
When playing Minecraft, you can play a singleplayer or multiplayer game. If you'd like to play with other people, there are two options: locating and connecting to the IP address of a multiplayer server, or opening your home or local area network (LAN) to other computers who are also connected to that network.
To play with someone on your network, first choose a host computer. This computer should be fast enough to play Minecraft, while running a server for other players as well. That player can create a new world, or select an existing one. Once inside that world, the host can push the Esc key, then click the Open to LAN button. Here, you can choose which game mode to set for the other players: survival is the default Minecraft, with life points and hunger, creative mode allows you to fly and place an infinite amount of blocks, and adventure mode is similar to survival, but players cannot place or destroy blocks. You can also choose whether or not to turn cheats (commands) off or on.
Once you have set these options, click Start LAN World, and you'll see a message that a local game has been hosted. Other players on the same network who wish to join can now start their game, select Multiplayer, and in a few moments their computer should automatically detect the game.
Playing on an online server A multiplayer server allows two or more players to play Minecraft together. You can either download the server.exe file from the Minecraft website, or connect to another person’s server. To connect to another player's server, log into Minecraft, select Multiplayer from the main menu, click the Add Server button, and enter the IP or web address of that server. Visit minecraft server list for more info. If you don't know the IP of a server, thousands of public servers can be located by doing a web search for something that suits your style of play.