unit Unit1; 

interface

uses
...
type
  { TForm1 }
  TForm1 = class(TForm)
    procedure Button1Click(Sender : TObject);
    procedure PageControl1Change(Sender : TObject);
    procedure Edit1Change(Sender : TObject);
    procedure Edit2Change(Sender : TObject);
    procedure FormActivate(Sender : TObject);  
  private
    { private declarations }
  public
    { public declarations }
  end; 

var
  Form1: TForm1; 

implementation

{ TForm1 }

procedure Button1Click(Sender : TObject);
begin
...
end;

end.