To make all the parts of items visible in the center pane, such as PDF attachments or web snapshots, select an item in the center pane, use the plus key on your keyboard...
...to collapse all items, use the minus key.
The Locate menu, the green arrow drop-down menu at the top of the right-hand pane in the Zotero client, helps you get additional information about references already in your library. It can also help you locate the full-text of article citations.
Here are three lookup options you'll likely see in the menu:
"Google Scholar Search"
It's important to have only one copy of each reference in your library. Usually, Zotero automatically locates duplicates so you can easily merge duplicate references at any time.
To merge duplicates:
Zotero may not automatically find all your duplicates, so you may find it useful to sort your library by title occasionally to catch any additional ones.
Zotero allows you to add notes to the references you collect. These are known as "child notes" since they're directly connected to a reference.
To create a note for a reference:
Notes can be seen as attachments under individual references, support formatted text (e.g. italics), and can contain web links. They are searchable as part of your Zotero library. Notes also save as you type.