There are two fairly good ways to find your old posts in this community:
- If you remember the last book you posted about, then you're best off using LJ Seek to search on the book title. Your entry should be listed among the search results.
- If you remember approximately the last time you posted, then I recommend using the Archive method of searching. The Archive link will take you to page showing the current year's calendar for this community. At the upper right corner of each calendar month, there's a link that says View subjects (example link goes to the July 2007 list). That shows you a list of every entry made during the month, and includes the user name and subject line of the post. You can do a standard text search (CTRL-F) to search for your own user name.
Once you find your entries, you can add them to your personal LJ memories for future reference by clicking the "Memories" link at the top of the page while you're viewing the individual entry.
Hope this is helpful!