You seem to be much too stuck so I wrote the entire command from the start. What I want you to do, is to tell us what you think each part does, and if needed, we'll correct you.
function serverCmdFling(%client, %target)
{
if(%client.isAdmin)
{
%target = findClientByName(%target);
%player = %target.player;
if(isObject(%player))
{
%player.setVelocity("0 0 250");
talk(%client.getPlayerName() SPC "has flung" SPC %target.getPlayerName() @ ".");
}
else
{
messageClient(%client, 0, "Player associated to client not found!");
}
}
else
{
messageClient(%client, 0, "You must be an admin to use this command!");
}
}