shut the forget up or yo as is going to be kicked
... If you mean in your server, i doubt he'll be there. If you mean this topic, you're confused. Anyways, you're going to need RTB or another Add-On like IGSO. or just use an Admin Pass. Set up a Password, and then tell your friedn or the person who you wish to give admin.
but evrybody will read the message and then bam everyone is admin
If that happens, then you did it wrong. Tell your friend it inperson (if you know them like that) Or via an Instan Messenger (If you are in contact with them) Or talk to them in game. Dont shout it out though, just say; /whis "Players name, without quotes" "Password/Message" They will get the message, no one else, and then you're done.