You now need to know the channel number you wish to add. "help Channels" for a list of ICC channels. To add the Experienced Help channel you would type '+channel 2' on the command bar under your Main Console.
To remove the Experienced Help channel you would type '-channel 2'
Type '=channels' for the list of channels you are currently in. (Or type 'vars'.)
Some of these channels are restricted to Groups. You have to be a member of such a group to enter these channels.
For more info about groups read "help group-commands"