How to Highlight
The easiest way to highlight text on a webpage is by simply selecting the text as usual. With the Diigo extension enabled with default settings, every time you select text on a page, a menu will display. The first option on the menu is to highlight the text. You can also choose the highlight pen from the annotation bar, which is opened from the Diigo extension menu by clicking "Annotate". This will turn your cursor into a highlighter pen. Anything you select with the highlighter pen will be automatically highlighted. When you are done highlighting, remember to click the highlighter pen in the annotation bar again to turn off highlighter pen mode.
To change the color of a highlight, you can change the color of the highlighter pen before you make a highlight by clicking the arrow next to the highlighter icon on the annotation bar and selecting a color, or you can change the color after the highlight is made. To change the color of an existing highlight, move your cursor over the highlighted text. A popup menu will appear just above the highlighted text on the left. Click the colored square icon to display the color menu. Simply select a color from the menu to change the highlight's color.
Delete a Highlight
You can delete a highlight from the same popup menu. Simply click the trash can icon.
Annotate a Highlight
You can add your comments to highlighted text by choosing speech bubble icon from the popup menu.