You can also use ZoteroBib if you just want to quickly generate some citations!
This is the same for the standalone app and Zotero on the Web
1) Sign up for an account at Zotero.org
2) Install the Zotero Connector for Chrome
The icon for the Zotero add-on will change to look like an article, book, a web page (blue-ish page), or other publication types depending on what Zotero can figure out about what you're looking at in your browser. Just click the icon and Zotero will automatically save the citation. Here's more information on how to do that.
If you're on a page of search results with many items, you'll see a folder icon instead. Click this to get a list of all the items on the page, and check off the ones you want to save.
Zotero will try to collect a PDF when you first save the item, but if it's unable to do so:
You will have to type your in-text citations or footnotes by hand (see the Writing Studio's excellent Writing Studio Citation Guide).