What went wrong:

CMD cannot find adb command in path path,
is because the adb.exe file exists in the android-sdk installation directory platform-tools/ subdirectory, and this path is configured into the environment variable.
Solutions:

Add environment variables as described in the book: C:\ Android-SDK-Windows \ Tools, then add
\
platform-tools to the environment variable

. For example, if The Android-SDK is installed in the root directory of C disk, then add the environment variable: C:\ Android-SDK-Windows \ platform-Tools