Assuming you already know you have perl installed in your system, can run a perl program, and know that the Spreadsheet::ParseExcel module is installed:
It looks like you can take the code in the "synopsis" and cut and paste it to be your test program. Copy it into a text editor and save it as something like "myexceltest.pl". this is your perl program.
Then take a simple excel file (maybe 4 cells by 4 cells, and fill them with numbers 1 through 16 in order) and save it into the same directory as your perl program that you just saved. For convenience you can save it as "Book1.xls", which is the name used in the example
Then you should be able to go to the directory that your program is in and run the program from there. (e.g. assuming you're on a unix system, type perl myexceltest.pl
If you haven't even gotten as far as running a perl program, tell us about your system and depending on what it is, someone will probably be able to point you to somewhere that will help you sort out how to do that first.