The Zotero Connector icon, located in the upper right of your browser, will change depending on the type of source information it detects on a page. Some common icons you'll see are for:
When you click the icon, you'll see a Zotero pop-up that confirms the item information is being saved to your library. If Zotero detects a PDF, it will save that, too!
Already have PDF files that you want in Zotero? Use the drag and drop feature! Select the PDF on your computer and drag it into your Zotero library. Zotero will pull the metadata from the PDF and create a parent item. If Zotero can't find the metadata, you can manually enter the information.
Penn Libraries requires you to sign-in to a proxy to access electronic resources. This isn't a problem with Zotero which supports proxy preferences. If you want Zotero to remember the proxy for future visits, accept the proxy.