Once you have data in your Zotero library, you may want to organize the data in a way that fits your understanding of your research. Zotero offers a number of ways to do this, including:
Collections function like folders within your Zotero library.
Tags link items together that have been assigned the same tag.
Zotero also offers you the option to indicate that items within your library are related to one another. Create links by choosing an item in your collection and using the Related tab in the right-side column. When you click Add you'll see a search box that you to choose an item in your Zotero library for linking.