Download the latest Gajim release from their site and install it.

  1. Go to our registration page and register an account there
  2. Open the Gajim application
  3. Go in the Edit menu and Choose “Accounts”
  4. In the “Accounts” menu click on Add and select “I already have an account I want to use.”
  5. On the next screen insert the Account details you specified during the registration remembering to insert lightwitch.org on the field after @
  6. You can either decide to “Remember your password” or not by checking or unchecking the appropriate checkbox
  7. Click next to commit your account creation
  8. After you completed adding your account on Gajim you’ll be able to log to the server and start communicating with your Jabber friends.

A few more references:

Joining a Multi-User Chat with Gajim: right-click on the “account name tab” select “Join groupchat” and enter the MUC Jid (“Jabber ID” the address for chats is usually in this format roomname@conference.domainname.com).