Clicking on any link opens an HTML page with the program.
Right click on page and use view source to see code.
The file upload examples are listed as text files to avoid priviacy and security issues.
(IO Press cannot host files users upload without conforming to the GDPR)
You can use pond.pcx to test the PCX program, page 246. Download it to a suitable directory and then use at as a local file to be processed.