[appleomax]

Код:

public OnPlayerConnect(playerid)
{   
     new string[128];
     format(string,sizeof (string),"Your text here");
     ShowPlayerDialog(playerid, 1, DIALOG_STYLE_MSGBOX,"Mission", string, "OK", "Esc");
     return 1;
}

And dialog id, which is 1 now, depends on what id you're using in OnDialogResponse