Writing a synopsis is a challenge. It can be kind of frustrating but also kind of fun jotting down all of the main parts of your books.
You should start by outlining your synopsis. What are the main things that happen in your book? Write down the main plot points. If you need a clear idea of everything that happened in your book, go through your book and write down what happens chapter-by-chapter. Then you can take what you have when you're finished and condense it to 1-2 pages.
Here are some links of examples and step-by-step instructions:
After you have your outline, put it all together. Make it sound exciting/gripping. It will take a lot of work to get it down to 1-2 pages, but you can do it! I swear. It sucks, but you got this! You're shortening your book to 2 pages or less, but hey, it's longer than a query letter.
The most important part is to tell everything that happens. Don't try to use some fancy words to keep the reader/agent guessing. Literary agents want to know everything. Yes, even the ending. The beginning, middle, climax, and ending all need to be included. Reveal it all in the synopsis!
The last part you should do is edit. Edit, edit, edit. Your synopsis is not perfect after your first try. You need to revise it a few times. After writing it, you should edit it, and then step back from it for a few days before coming back to edit it again.
Sorry for not posting for a while, but good luck with your synopsis!