Choose 'Keywords' from the Tool menu, or use the keyboard shortcut <Command> <K> (for Macintosh) or <Control><K> (for PC), to display the Keywords window. (Click on 'Show Example', above, to see what to expect.)
You can use the letter tabs on the left-hand side to jump down the list of keywords, to help you find the word you are looking for.
By choosing a keyword you can find out which Subjects and Sections (and sometimes Topics) contain material that's relevant to that word, and then go to that place by clicking on the 'Go to...' button.