You can get synonyms from the main text screen or the Word Frequency pages by

• clicking a word with the right-mouse-button,
• entering the word in lower case in the entry widget and pressing the Find Synonyms button

In either case, after a moment a new window will appear with a list of synonyms for that word.

Sometimes a synonym cannot be found because you are clicking on a derived word (like ambushing, instead of ambush).

If you have the Word Frequency display open when this happens, you can type the base word in the bottom synonym entry box. If that window is not open, you can add a temporary word to your text, click to find a synonym for the base word, then clean up your main window.