Are you trying to launch it using Wii Menu? If so, the "app" is likely just a forwarder, which will require the app to exist on the SD card.
So first, launch HBC to see if you can see it there, if you don't, that's your problem. You don't have the app (at least properly installed if not at all) on your SD card, placing it in the right place will help.
If you see it in HBC, try launching it from there to see if it works. If not, then something else is wrong and you likely need to remod your system to clean it up. If that works, then something is wrong with the forwarder.
If you don't have the app on your SD card, I have links to WiiFlow, CFG, and GX in my signature.
If you have to remod your system, see the Softmod Any Wii guide linked in my signature. At the end of the guide (Chapter 3) you get an App Pack that has recent (though not always most recent) versions of the three USB loaders. Make sure they get installed to your SD card properly, overwriting or deleting any previous versions you may have).
If you think you did stuff right and it still isn't working, my signature also has a link to show you how to generate and post a syscheck. Do so and we will see what that system of yours looks like and can give you recommendations on what to do based on that.