The digital reading log is a feature that is reserved for Whooo's Reading Silver and Gold licenses.
To log your reading, first search for your book in your Whooo's Reading account by typing the title into the search bar at the top, like this:
Select the correct book (or add it manually), then choose I'm still reading if you have not yet finished the book, or I finished if you have read the whole book:
Then choose Log Reading on the right:
Type in the number of minutes and pages you read and choose the day you did that reading. Click Log More for this Book if you read more than once. Click the Log Reading! button to submit the reading to your reading calendar: