You installed
BootMii, not HackMii. HackMii is the blog where the team behind BootMii and HBC post stuff. It also lends it's name to "The HackMii Installer", which is used to install BootMii and HBC.
Anyway, sounds like you didn't actually install HBC. If you did, it would show up in the System Menu (the screen appears when you select "Wii" in BootMii). You need to run the HackMii Installer again and install HBC this time, as well as BootMii.