Easiest path: install MyFeeds from inside WordPress in two clicks. If you'd rather upload the ZIP yourself, that works too. Instructions for both routes below.
Log in to your WordPress site. You should land on the Dashboard, the main admin page with the sidebar on the left.
In the left sidebar, hover over Plugins and click Add New Plugin. You'll see the WordPress.org plugin directory's search bar at the top of the page.
Type MyFeeds into the search box. The plugin titled MyFeeds — Affiliate Product Feed Manager appears in the results. Click Install Now, then Activate once installation completes.
Click MyFeeds in the sidebar, then Add Feed. Paste your product feed URL, give it a name, and let the import run in the background.