Channels are both simple and complex. This page will be a reference of all the major features of channels. The information here will be for the irc.mibbit.net server.
To register a channel, be sure to have your nick registered. Then use the command /msg chanserv <#chan> <Channel Password> <Channel Description>. The user using the command must have Op or higher to use the command. Entering an empty channel will give a user op if it is not registered.
To identify what a channel is about, there is a thing called the "topic". This topic shows up when joining the channel, and also shows up when you type /list on a server.
To change it, a user will need operator privileges in the channel. Then, in Mibbit, the user must type /topic New Topic
Example: /topic This is a test channel