Object creation in Implementation section...

unit Unit1;

interface

uses
   ...;

type
  TSample = class (TObject)
  private
    privatevar: vartype;
    ...
    procedure privateProc1(myparam: paramtype);
    ..
  public
    publicvar: vartype;
    ...
    procedure publicProc1(myparam: paramtype);
  end;
  //you'd have to implement all of TSample's methods in Implementation section also.


  //assuming TSample is part of Form1

  TForm1 = class(TForm)
     //all your form's objects and methods
     procedure FormCreate(Sender: TObject);
     //You can create a TSample in FormCreate...
     procedure FormClose(Sender: TObject);
     //Destroy TSample in FormClose...
  private
     //Declare an instance of TSample Here
     MySample: TSample;
  public
    { Public declarations }
  end;

implementation
{$R *.DFM}

{TSample}//TSample Methods are implemented

procedure TSample.privateProc1(myparam: paramtype);
begin
    //implementation of TSample methods
end;

procedure TSample.publicProc1(myparam: paramtype);
begin
    //implementation of TSample methods
end;

{TForm1}//TForm Code implmentation

procedure TForm1.FormCreate(Sender: TObject);
begin
   MySample := TSample.Create(nil);
end;

procedure TForm1.FormClose(Sender: TObject);
begin
   MySample.Free;
   MySample := nil;
end;

end.