Title: Create timer
Use Timer component and this code:
var
MyTime: TDateTime;
...
procedure TForm1.Button1Click(Sender: TObject);
begin
Timer1.Interval:=1000;
MyTime:=Now;
Timer1Timer(Timer1);
end;
procedure TForm1.Timer1Timer(Sender: TObject);
begin
Label1.Caption:=TimeToStr(Now-MyTime);
end;