The first way to get the Homebrew Channel was with the Twilight Hack. However, the system
menu 4.0  disabled the Twilight Hack, so Homebrew won't work.
But there's another way to get Homebrew if you have 4.0 or above. It's called Bannerbomb.
It's a new way which uses an exploit in the Wii System Menu (so that it only requires an
SD card).
So... I guess you might want to download it. But first I must give some warnings.
Well, if you don't know what Homebrew is, then you probably shouldn't be getting it
anyway.
If you have purchased your Wii in 2009, there may be some problems. If your Wii starts off
with the serial number lu64 or lu65 (which can be found at the bottom of your Wii), then
there's a chance that your Wii could *brick after you download the homebrew channel.
However, that chance is very unlikely because of the new HackMii installer checks before
an installment to see if it's possible.
*Brick means that the Wii will not function properly. If you brick your Wii, then you
won't be able to use it. It won't be useful for anything. It's just dead. If you are too
scared of getting your Wii bricked, don't download the Homebrew channel.
Also if you have downloaded the Homebrew channel, DO NOT UPDATE YOUR WII. If you update
your Wii, there's a possiblity of your Wii getting bricked. And it's not a small
possiblity either.
I guess that's all for the warnings. Really though, if you're scared for your Wii, do not
download the Homebrew channel.
Anyway, the download and instructions are *here, but I'm going to explain it in a
different way.
* http://bannerbomb.qoid.us/
So you must have something that you can put SD cards into. Either just a computer with
that function, or an SD card reader. You also must have *Winzip.
* http://en.wikipedia.org/wiki/WinZip
http://www.winzip.com/index.htm
Unfortunetly, if you can't get it, you can't get Homebrew. :(
Unless you get someone to unzip it for you, of course.
So you have an SD card. If your SD card has Homebrew apps n' stuff already on it, then you
should probably copy them all into a folder on your computer, and when you're done, just
put them back onto your SD card. If it has a folder or something called "private" rename
it to something else. It doesn't matter.
After that, click aad1f_v108.zip on the link above and put it on the root of your SD card,
then unzip it (right click, then choose extract to aad1f.etc). Open that folder up, and
copy the "private" folder and paste it onto the root of your SD card.
After that, download the HackMii installer (in the link). Unzip that, then go into the
folder. Find 'installer.elf', copy it, then paste it to the root of the SD card, then
rename it to 'boot.elf'.
Then pretty much everything should be perfect.
Without putting the SD card in your Wii, turn it on, go to (Wii) on the bottom left, then
Data Management, then Channels, then SD Card. When you're at SD Card, put the SD card in
the slot, and a message should pop up. If the message does not appear, or your Wii freezes
(which is okay), then you'll have to download another zip file on the link.
Also visit these other links:
http://en.wikipedia.org/wiki/Homebrew_Channel
http://wiibrew.org/wiki/Bannerbomb
http://en.wikipedia.org/wiki/Brick_(electronics)