On page 9, of Git in Practice (C) 2015, there is a command given to add everything in the current directory and its subdirectories to the staged area. This should be: git add .
(With a space between add and dot)

Thanks for the report, added to Errata in https://github.com/GitInPractice/Errata/commit/18b509efbafc7a857e0820b15a14b815567338dc. Sorry for the delay!