I have no clue how to work with open source?

I downloaded a program (or I thought it was a program) to archive my old entries in my blog and transfer into hard copies. The description says it’s open source. I opened the folder and all that’s inside of it are PHP files. I have no clue how to "activate" or open these files, let alone use them. Do I need to download a specific application? Do I need to have Linux?