The Zotero desktop application is a powerful piece of software. Sometimes, though, you may not have access to your desktop application. No problem! It's still possible to save, organize, and edit your citations by simply saving them to your Zotero online account. Note: Browser connecter(s) must be installed for this method to work.
1. Login to your Zotero account
2. Check for the browser connector. Is it installed? Look for the capture icons near the browser's address bar. Install the appropriate browser connecter from the zotero.org website if necessary.
3. To add an item to your library, click the capture icon as you normally would when using your desktop application.
The screenshots below show two popup windows you are likely to see when you first attempt to add to your online library:


Just remember...your online library looks a bit different from your desktop library and it cannot perform all the same functions.
