You can't, there's no whisper function, just general broadcast, unless you are on a multiplayer server which has a specific plugin to let you do it (the server will tell you how).
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IMPROVED BY N80SIRE
You can do a simple command:
/tell <player> <message>
it will show up in chat as <user> whispers:<message>
You press T to talk.
George sometimes tells people that Lennie is deaf and that is why he doesn't talk much.
How? You can't.
You Can If You Press T
no, but you can do a skype or hangout with who you are playing with while you are playing minecraft with them.
Yes you can.
When you talk about someTHING rather than someONE, use "it" instead of "he" or "she".
you can press T to talk
Rcon allows for a client to talk with the minecraft server (think remote console)
Press 't' to talk.
You can type to other people on the same server by pressing T for talk. If it doesn't work, press esc, then options, then controls. Change Chat to whatever button you want to use to type.
None hates minecraft