The easiest and most straightforward way to add content is to use the browser icon that appears in the address bar area after you've installed the Zotero Connector. To save the reference, click the icon.
Some pages may contain multiple items and a folder icon will appear in the address bar.
Clicking on the folder will reveal a pop-up window which will allow you to select which resources you would like to save to Zotero.
If you have your content organized in folders, Zotero will attempt to save the content in the last active folder. You may click the drop down menu and select a different folder if you wish.
If you do not have the Zotero desktop application open, you'll receive a message similar to the one below. For best results, open the application and proceed. If you are unable to open it (maybe you are on another computer that doesn't have the application installed), and you've set up an online account, you can click the Enable Saving to Online Library to add the content to your zotero.org account. If you have syncing enabled, when you open your Zotero desktop application, the content should show up there as well.
The quickest way to add PDFs to Zotero is by turning on the feature to automatically add them. Make sure that the feature is enabled in Zotero by selecting Edit > Preferences and checking the box next to the option Automatically attach associated PDFs and other files while saving items. Click OK to save the changes.
You may also save your PDFs to your computer. Open Zotero and then drag and drop them into your collection. Zotero will automatically try to retrieve the metadata for the PDF if it has been creating using OCR (Optical Character Recognition). Refer to the Zotero Documentation for more information on Zotero's PDF features.
There are other ways to add content into Zotero. You can save as a webpage, import data from other tools, add items manually and/or add items using ISBN, DOI or PubMed identifiers. For more information on adding items to your Zotero account, please see the Adding Items to Zotero section of the Zotero documentation.