Assuming you know the title and author of the book you're looking for, the easiest way to find it on Amazon is to do a search for it. Just go to Amazon's homepage and enter the book's title into the search bar. If the book is available on Amazon, it should come up in the search results.
If you're having trouble finding the book, make sure you're including the correct title and author name. Sometimes book titles can be tricky, so if you're unsure, you can try doing a search for just the author's name to see if that brings up the correct book. If you're still having trouble, it's possible that the book you're looking for isn't available on Amazon. In that case, you might try checking out a different online bookseller, like Barnes & Noble.