If you guys are on some network, it can get a bit complex. But there's a way to fix it of course.
You can whisper to your friend using this : /w "AccountName" "Message".
Here's the full list of commands :
/help - (Ex: /help whisper)
Displays usage help for chat topics.
/whois [user] - (Ex: /whois TPark)
Looks up some basic information on a user, including their account number and their current location. This is an excellent way to find your friends online. typing /whois #[number] (E.G. /whois #1).
Aliases for this command : /where /whereis
/whoami - (Ex: /whoami) - displays your information on Battle.net.
/w [user] - (Ex: /w JohnS)
Sends a private message to a user online regardless of the channel they are in. This is an excellent way to let a friend know you are online.
Aliases for this command: /msg /whisper
/ignore [user] - (Ex: /ignore BFitch)
Ignores any future messages from that user effectively muting that user to you.
Aliases for this command: /squelch
/unignore [user] - (Ex: /unignore BFitch)
Allows a previously squelched user to talk to you normally.
Aliases for this command: /unsquelch
/away [text] - (Ex: /away eating dinner)
Displays a message that you are away from your keyboard whenever someone whispers to you or does a /whois command on you. To disable this command, use the command again.
/dnd [text] - (Ex: /dnd sorry playing a game with GFraizer)
"Do Not Disturb" - prevents ALL whispers from displaying to your screen. Its use is similar to the /away command. To turn the DND mode off, just type /dnd without a reason. This will prevent people from sending whispers to you while in a game as well. You are still able to see all normal public channel messages.
/who [channel] - (Ex: /who Open Tech Support)
Displays a list of all users in the given channel.
/stats [user] ID - (Ex: /stats DavidN STAR or /stats #42 STAR)
Displays the player's Win/Loss/Disconnect record for both normal and Ladder games.
STAR - StarCraft
SEXP - StarCraft Expansion (Brood War)
W2BNE - Warcraft II Battle.net Edition
/users
Displays the number of users currently on Battle.net.
/time
Displays the current Battle.net time.
The following commands can only be used while in a chat room.
/join [channel name] - (Ex: /join Blizzard Tech Support)
Switches to a channel without having to use the channel join screen. Aliases for this command: /channel
/me [text] - (Ex: /me is rolling on the floor laughing!)
Displays emotion text, as in "PatN is rolling on the floor laughing!"
The following commands can only be used by channel operators.
/designate [user] - (Ex: /designate AlenL)
Selects [user] as the next channel operator when you step down, either by resigning or by leaving the channel. If the channel Operator leaves the channel and has designated more than one person, the last person designated will have ops.
/resign
Step down as channel operator and become a normal user again.
/rejoin - (Ex: /rejoin)
makes you rejoin the channel you are currently in.
/kick [user] - (Ex: /kick TwainM )
Kicks a user out of the channel. This is best used as a warning since a kicked user can return at their leisure.
/ban [user] - (Ex: /ban RobertB)
Kicks a user out of the channel and prevents them from returning until the current operator steps down or leaves the channel. This is the most powerful command at an operator's disposal, use it wisely.
/unban [users] - (Ex: /unban RobertB)
Allows a banned user to return to the channel.
Shortcut keys
CTRL-X
Cuts the selected text
CTRL-C
Copies the selected text
CTRL-V
Pastes the selected text
CTRL-A
Select all text
CTRL-N
Diablo II: Pastes the name you have selected
ALT-N
Diablo, StarCraft, and Warcraft II BNE: Pastes the name you have selected
/d2notify
Diablo II: Toggle channel enter/leave notifications
ALT-V
Diablo, StarCraft, and Warcraft II BNE: Toggle channel enter/leave notifications
ALT-W with user selected
Diablo, StarCraft, Warcraft II BNE: Sends a private message to the selected user.
Aliases for this command: /w /msg /m /whisper
TAB
Diablo II: Cycles through the last 10 commands
StarCraft: Displays the last command then cycles through the users in the current channel.
CTRL-M
Diablo II: Toggles music on Battle.net and the main menus