To find out how to get the homebrew channel on your Wii that is below firmware version 4.2, click here (bannerbomb tutorial). Since you have a Wii that is below 4.2, you do not need to softmod it (aka restore the trucha bug).
Bannerbomb is an exploit capable of launching homebrew from any version of the System Menu. It was created to replace the Twilight Hack, which does not work on System Menu 4.0. The exploit works by using a malformed banner to crash the Wii and run code to load the boot.dol