Decrypt9 is for decrypting games and sections of the NAND etc.... In the case of the tutorial you're using, it's being used to dump the health and safety app. From there, you can inject BigBlueMenu (a cia installer) over the health and safety app. Then, after you boot into CFW, the health and safety app will launch BigBlueMenu instead of the health and safety information.
Are you on section 4a of the tutorial? If so, you could just set up the
Homebrew Launcher and do section 4b instead. 4b seems a bit easier.