For the purposes of this demonstration, the desktop version of Zotero will be used. First, double-click on the PDF to open it in the PDF viewer. You will get a screen that looks similar to this:
You have a set of tools in the middle that include, from left to right: highlighter, notes, and textbox. The fourth item allows you to choose a color. Note that yellow is the color selected.
You can highlight a section and then add a note. To add the note, click on the part that you highlighted. The note textbox pops up on the left side of the screen. You may need to click on the textbox in order to type your desired note into the box.
You can also add a virtual sticky note. Click on the "Add Note" button (2nd button) and then click on the place where you want the note to go. A sticky note icon will appear in that spot. After you place the virtual sticky note, you will also see a note textbox open up on the left side of the screen. Type the desired text for the note in the box.
You can also box a piece of text. Click on the "Select Area" button (3rd button). Use your cursor to place the box around the desired text. Then, either click on the box that you have just placed around the text, or click on the note textbox that has appeared on the left side. You will then be able to type the desired note into the textbox.
You can see all of the notes that you have added in the note textboxes by selecting, "Show Annotations."
You can edit your notes by clicking on the three dots next to the page number. You have the option to "Add to Note," change the color of the highlight or sticky note, "Edit Page Number," or "Edit Highlighted Text" (note that this last one is for highlighted texts only and not for sticky notes).
Zotero automatically saves the notes and highlights so that they are present any time that you open the document in the DESKTOP version of Zotero.
For more information on using the annotations feature, go to https://www.zotero.org/support/pdf_reader.
If you’re using a mobile device or a desktop browser without a Zotero Connector, you can use the Zotero Bookmarklet to save items to your Zotero library. Zotero recommends using the Zotero Connnector when possible for the best experience.
On mobile devices and in Safari and Internet Explorer on the desktop, the bookmarklet will save to your online Zotero library. In Microsoft Edge, the bookmarklet can save to the local Zotero program on your computer and will allow you to choose a target collection and add tags to items, just as you can with the Zotero Connector.
The process for installing and using the bookmarklet varies depending on the browser you are using.
To install, click and drag the button to your browser’s bookmarks toolbar.
javascript:var d=document,s=d.createElement('script');s.src='https://www.zotero.org/bookmarklet/loader.js';(d.body?d.body:d.documentElement).appendChild(s);void(0)
javascript:var d=document,s=d.createElement('script');s.src='https://www.zotero.org/bookmarklet/loader.js';(d.body?d.body:d.documentElement).appendChild(s);void(0)
javascript:var d=document,s=d.createElement('script');s.src='https://www.zotero.org/bookmarklet/loader.js';(d.body?d.body:d.documentElement).appendChild(s);void(0)
javascript:var d=document,s=d.createElement('script');s.src='https://www.zotero.org/bookmarklet/loader.js';(d.body?d.body:d.documentElement).appendChild(s);void(0);
The information on this page is drawn directly from: https://www.zotero.org/download/bookmarklet.