Copy & paste the proceding PHP code into your file:

<?
if(file_exists("counter.dat"))
{
  $exist_file = fopen("counter.dat", "r");
  $new_count = fgets($exist_file, 255);
  $new_count++;
  fclose($exist_file);
  print("$new_count people have visited this page");
  $exist_count = fopen("counter.dat", "w");
  fputs($exist_count, $new_count);
  fclose($exist_count);
}
else
{
$new_file = fopen("counter.dat", "w");
fputs($new_file, "1");
print("1 person have visited this page");
fclose($new_file);
}
?>

Create a text file called counter.dat with "0" as the only content. Upload this file into your directory and make sure it has permission of 777 (CHMOD 777).