You and your Mac-holding friends have gathered and now you want to share files. Did you remember to bring an Ethernet switch or hub (which is basically a box you can hook all your computers up to), and enough Ethernet cables for all your computers?
That's ok, you can easily create an ad-hoc wireless network that everyone can join.
From your menu bar, select the AirPort icon. It looks like a series of curved lines rising from smallest to largest. If it isn't there, go to System Preferences > Network, and check the box next to "Show AirPort status in menu bar."
From the AirPort options, click on Create Network. You'll get a box that asks for a network name and channel. Leave the channel on Automatic unless you have a reason to do otherwise. (In which case you're probably not reading this article.)
You are also offered an option to require a password.
Enter a name for your network, and, for security purposes, require a password of your choosing. When you check "Require Password," you'll have to type a password twice. You're given the option of 5 ASCII characters or 10 hex, which means you can use 5 regular characters (letters and numbers) or convert an ASCII phrase into a more secure 10-digit hex code. Next, choose a security type. It will default to 40-bit WEP, which is more compatible. Share the password with your friends.
Click OK. The AirPort icon in the menu bar will change, now it looks like a little computer in a wireless signal field.
Now, each user should click on their AirPort icons. Your network will appear as a connection option. They should select your network and type in the password you chose.
That's it. Now you can share files without all the muss and fuss of Ethernet cables.