Add a Plug-in to my Magento Cart -- quirky

I run an outdoor sports website called http://OutYourBackdoor.com. I have a Magento online shopping cart installed on it. It has 400 products, but they are only partially completed. They are all missing photos and descriptions. I have an Ebay Store with the same products which are completely finished. There is a plug-in called M2E which synchronizes a Magento cart to Ebay. But it can't go the other way! BUT a year or two ago the M2E plug-in COULD go the other way and import Ebay Store items into Magento. I have acquired the files from the OLD plug-in and would like to see if I can add that old function to my Magento cart. But I don't know how to upload them properly to test them to see if the old plug-in will work. A person online gave them to me but now isn't available to tell me how to install them! He emailed me the plug-in in a folder which includes two other folders, one says "step 1," the other says "step 2." The contents of the folders look like Magento items, but I don't know how to install it or test it (if it doesn't work I want to be able to undo it without hurting my cart). It kind of seems like M2E might have sold the Ebay -> Magento function to another company which makes a $200 product called "E2M" which does what I want, but I can't afford it. I have $40 for this project.