Adding a public channel
1. On the blue navigation side-bar, select the "+" next to "Channels". Then provide a name and purpose for your channel.
2. Enter the channel by selecting it from the list on the blue navigation side-bar.
3. To invite other users to the channel, select the "Invite others to this channel" link above the "Write a message..." box at the bottom. Select the users you want to add, and you're all set.