I viewed a video which states there is an arrow to the left of the item in the Zotero library where I can read the PDF and make notes, but there is no arrow visible.
There would be an arrow if there was a PDF. But you don't need to expand the parent item to open the PDF or take notes — you would just need to double-click the parent item or add a note from the toolbar or right-hand pane.
Read through Adding Items to Zotero to make sure you understand how to add files and notes.
If you're still having trouble with something after reading through that, take a screenshot, upload it somewhere (Google Drive, Dropbox, etc.), and provide a link here and we can take a look.
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Read through Adding Items to Zotero to make sure you understand how to add files and notes.
If you're still having trouble with something after reading through that, take a screenshot, upload it somewhere (Google Drive, Dropbox, etc.), and provide a link here and we can take a look.