Maybe it hasn’t updated yet or maybe it’s missing a date read, or maybe you read a book twice, or maybe a book is showing up twice. Goodreads chooses not to update some things immediately for performance reasons.
The 2011 Challenge image on the home page doesn’t always update immediately, but will show the current number if you click on it. If the number still isn’t what you expected, check the date read on each book. Only books with a date read in the year 2011 will count for the challenge and all books with a date read in 2011 will count, even if the books aren’t on your read shelf. So if you don’t want a book to count, just leave that date blank.
The books on the stats page (accessible from the my books page, bottom left) are also counted and sorted by the date read. The stats page is only updated once a day, so don’t worry about the ones you just entered, they’ll show up tomorrow. For books you read years ago, you can just guess at the year you read them to get them to show up. Details will display the books you read in that year divided by the star ratings. View books gives you a shelf view with only the books you read in that year selected.
To add or edit the date read for your books, go to the my books page, select your read shelf and you can add or change the date by clicking on the word edit under the date. You can also sort the shelf by date read by clicking on the heading, so that you can find the books that don’t yet have a date read.
You probably want to run the duplicates function occasionally (also bottom left of the my books page) to make sure you haven’t accidentally added the same book twice. You may want to add some books twice, if you read two different versions or just to count a reread. The only way currently to count a book twice, is to shelve or rate two different editions of the book.