2. Create a new folder somewhere and put the jar in it. Then run it.
It will create a few files, then close. This is because you need to agree to the EULA. Open eula.txt, set eula=true, then save.
3. Launch the jar applet again. It will create the rest of the files, including the world.
4. Time to configure. Set online-mode=false.
Configure the gamemode, difficulty, pvp, etc, to your preference. More info on the server.properties at
5. If you want to play in an existing world, replace the existing "world" folder with your world and name it "world". If you want to play in a new world, then use the world that is already there. If you do not like the seed of the world and want to regenerate the world with a new seed, just delete it. If you want to generate a world with your own seed, put in the seed in the server.properties after where it says "seed=" and delete the world.
Now your server is setup! To stop the server, enter "stop" in the console. To start it, launch the jar applet.
If you would like to download a pre-made server with the files already generated and the online-mode false, download here.
Now that your server is setup, it's time to play on it!
For you to connect to the server, use "localhost".
For other players to connect to the server, first they need to be connected by a computer-to-computer network (If you haven't setup this already, read below). Find the INTERNAL IP of your computer that is hosting the server.
On Mac OS X
If you are using Wi-Fi, hold option key and click the Airport menu. Use the IP Address shown just under the Wi-Fi network you are connected to.
If you are not using Wi-Fi or above doesn't work:
Open System Preferences and go to Network. It will show you the internal IP of your computer. If it has not created an IP address, wait a bit.
On Windows, Open Network Connections by clicking the Start button , and then clicking Control Panel. ... Select an active network connection, and then, in the toolbar, click View status of this connection. ... Click Details.
Use this IP to connect to the server.
How to create a Computer-to-Computer network
Mac OS X:
Click the Airport Icon in the menu bar and click "Create Network..."
Create a network. Choose whatever name you want, but remember that the network will be broadcasted so everyone can see it. Put a password on it too. Choose 40-bit WEP.
Open Network and Sharing Center by clicking the Start button , and then clicking Control Panel. In the search box, type network, and then click Network and Sharing Center.
Click Set up a new connection or network.
Click Set up a wireless ad hoc (computer-to-computer) network, click Next, and then follow the steps in the wizard.