First things first, you'll need the multiplayer software. This isn't too hard to get, it can be found on Minecraft.net where you originally purchased the game. It's generally assumed that if you have this software, you can play multiplayer. This isn't so. For some untold reason, many people, including us, aren't able to connect with this software. The following instructions will walk you through what you need to do to access multiplayer on Minecraft. If you intend to host your own games, read from Hosting, if you only aim to join a friend, the host section can be disregarded.

Go to the Minecraft website. Click the Download button under the spot regarding multiplayer and scroll to the bottom. STOP! On your desktop make a new folder called My Server (the name doesn't matter). Now back to minecraft.net, click the first download called Minecraft_Server.exe.
Save it to your new Server folder on your desktop, but make absolutely sure the file is an .exe or this will not work. Now if you did this correctly, the .exe file will be the signature Minecraft Grass Block. Barline this window, and open an internet tab and google "Logmein Hamachi". This is a quick and safe download that will fully open up multiplayer capabilities, but the hosting software is still not set up. Once Hamachi has opened, if you intend to host, then click the option for create a new network, if you intend to join a friend's, select join a network. Now click that old minecraft grassy block. Disregard the "failed to" messages, thats just the file making
option .txt files in the folder. Now the following steps are crucial.


(The following steps are all located in the My Server file that you made.)

Step 1: Click server properties
(may not say properties but it's there. Open with wordpad for best results).

Step 2: Make sure that
server-port=
and
server-port=
both have this setup: server_setup=25565server_setup=

Now here is where you go back to you Hamachi. Whatever is next to your name is put here.
The rest of the options can be set to true(yes) or false(no). Save file and exit.

Step 3: Click "Ops". This is where you select users to be Admin.
Put in your minecraft name exactly how it is, as well as any other friends who
you want to be admin. Now save and exit.

Step 4: Banned IPs and Banned players. Banned IPs aren't exactly what you would expect them to be, it's items you don't want in your game. Such as TNT, Minecarts, Fire, ect
Put the data value (located under KNOWLEDGE) and save.
Optional Step: Whitelist is where you put the names of people you want to join. This means
that you're making your server private. In server properties put whitelist as true and that
completes the step of privacy.

Step 5: Now once again run the server .exe. This will get everything ready.
(If it says "failed to" the find the one you missed).Let the spawn area load.
This will be the end of the server setup. Now your ready.

Close the .exe file and then re-open it. Got to minecraft.net and
put your server ip in multiplayer and that's it, your in.
(If any problems occur then read through this process and find the mistake.)

Fortunately, joining is far simpler than hosting, and is as easy as 1 2 3. However, you must connect to a friend who has functional hosting capabilities.

1: Locate software known as Logmein Hamachi, it is a completely safe and quick download that can be found in a google search. We completely reccomend it.

2: Download this software, and it will open. Once it opens, it will prompt you to either Create a Network or Join a Network. You want to join a network, and enter the Name and Password of your friend's network.
 
3: Once you've done this, you'll see your friend's name and his IP address,
enter his IP into the text box in your Minecraft Multiplayer section, and have fun!