The extension will let you import references (both individual articles and search results pages) on a website, or database like PubMed, Google Scholar etc.
To make a highlight, simply select the text to highlight, and you'll see a colour palette appear:
Once you've chosen a colour, your highlight will be saved and you'll see the option to add a note:
Once your highlight/note has been saved, you'll be able to view it in the extension window, and also by clicking on the highlight in the text:
You can jump to the highlighted section at any time simply by clicking the highlight in the extension window, or by clicking the 3 dot menu and selecting 'Jump to highlight'. This menu also gives you the option to copy the highlighted portion of text, or delete the annotation:
Clicking the 3-dot menu in the popup in the text will give you the option to edit or delete the annotation, or view it in the Lean Library Workspace site: