When you supply your own cell handler you don't need to iterate through the workbook sheet by sheet and cell by cell.
The iteration will occur automatically when you call the Parse() method. As such you don't need any of the code below:
my $oBook = $oExcel->Parse($file);
I can post a more complete example if you define a little more clearly what you are trying to do. It looks like you are trying to extract the cells in the first column of the first worksheet and print them as in a Html format but perhaps you can go into a little more detail.