You should be able to find most of what you need at Zotero's website, in this documentation section. The information in this section (actually most of this Resource Guide) is intended to supplement what is on the official website.
Other Guides and Tutorials
This research guide has a lot of information, and the Zotero website is packed full of how-tos, but you may want to look at one of these other library Zotero how-to sites
*highly* recommended. The guide author, Jason Puckett, published the 2nd edition of "Zotero A guide for librarians, researchers, and educatiors" in 2017.
