It is not ISO.It's IOS.Two very different things.
Now,your error means that Homebrew Channel has no IOS to work with.And he needs patched ios 36 or 38.
So you need to download this:
Free File Hosting. SharingMatrix.com file hosting and storage.
-Now create folder called "apps" on the root of an as card(sd/apps)
-Now put cIOS38r17-Installer in apps folder
-After that,copy IOS38-64-v3867.wad to a root of an sd card(sd/IOS38-64-v3867.wad)
-Now launch homebrew and run Cios rev 17 installer
-Select Wad Installation and install it
But before all this,tell me did u install Homebrew Channel?Do you have it at Wii Menu?Otherwise,how the neck are u launching Homebrew?