Not all HDs are compatible, be sure to check if the one you want to get is compatible. Here at wiihacks there is a compatibility list somewhere.
Wiiflow_NForwarder.zip is a forwarder channel for the application. It installs as a WAD file via WAD Manager and shows up as a channel on the home screen. When launched, the channel looks for and loads the application from an SD or USB device.
If you need more detailed instructions than are provided on the Google site for setting Wiiflow up, along with specific downloads, there is a guide linked in my sig. below.
I am a noob who successfully modded my Wii. I am still in the dark about a lot of this stuff but I am learning fast. Not trying to hijack this thread but after reading it all I need to ask a couple of things. I used the bannerbomb hack to softmod and the guide I followed had me install USB Configurable. I would like to put WiiFlow on but I am not sure how. I downloaded the Full version of it and read where Teknix2600 recommended putting the .wad file on my SD card. This is where I am lost. There are 12 .wad files in the folder from WiiFlow. Do I put all these .wad files in my WAD folder on my SD card? My Wii is version 4.2. Thanks for your help in advance.