Use Spreadsheet::ParseExcel.

Start by reading in the contents of your first spreadsheet. Let's assume you're using worksheet titled "gendata".

  use strict;
  use Spreadsheet::ParseExcel;

  my $oBook = Spreadsheet::ParseExcel::Workbook->Parse('first.xls');

  if ( ( ! $oBook ) || 
       ( ! defined( $oBook->{Worksheet} ) ) )
  {
    die( "Cannot parse first spreadsheet" );
  }
  my $sheetone = $oBook->Worksheet('gendata') ||
    die( "No such worksheet gendata" );
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Then read in the contents of the second spreadsheet (let's assume you're using worksheet titled "gensearch"):

  my $oBook2nd=Spreadsheet::ParseExcel::Workbook->Parse('second.xls');

  if ( ( ! $oBook2nd ) || 
       ( ! defined( $oBook2nd->{Worksheet} ) ) )
  {
    die( "Cannot parse second spreadsheet" );
  }
  my $sheettwo = $oBook->Worksheet('gensearch') ||
    die( "No such worksheet gensearch" );
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Next let's assume that you want to search all the strings in the first 10 rows of column A in workbook two against the same column/row in workbook one.

  for ( my $row = 0; $row < 10; $row++ ) {
    my $search = qr/$sheettwo->{Cells}[$row][0]->{Val}/;
    my $data = $sheetone->{Cells}[$row][0]->{Val};
    if ( $data =~ m/$search/ ) {
      printf( "Column A Row %d matches\n",
              ( $row + 1 ) );
    }
  }
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