Use ModMii. It's an interactive download wizard for your Windows PC. It downloads every file you'll need to softmod your Wii and sets up an SD card for you, bricking is *almost* impossible. This sets up your Wii completely stable and internet enabled. Firmware version doesn't matter. Project homepage is HERE. Go to the download section and get the latest version (4.8.2 atm).
Short Tutorial from wiihacks.com
Introduction: What is ModMii?
ModMii, formerly known as NUS Auto-Downloader, is able to download all the files needed to modify ANY Wii (4.3U/E/J and Below & 4.2K and Below); it can generate custom guides based on your Wii's specifications, and save the files to your SD Card in their appropriate locations for easy offline softmodding.
Literally run the program once, let it download, and you have all the files you need on your SD card to modify your Wii
What can ModMii do?
It can download all the files necessary to Modify, Upgrade & Downgrade your Wii System Menu
Download individual IOS/cIOS files, cIOS & cMIOS installers, Official Wii Channels, System Menus, Multi Mod Manager, YAWMM, Dop-Mii, both versions of Bannerbomb, Hackmii Installer etc.
Install patched IOSs without an wifi connection on your Wii
This includes an easy to follow Custom guide to setting up a USB-Loader (including how to format/partition your external hard drive)
Install SNEEK, build SNEEK NAND dumps, and Batch Extract Wii Games for use with SNEEK+DI or UNEEK+DI
Customize Bootmii, Wad Manager and MMM start-up settings using ModMii Configurators to create a custom config files
This is also capable of downloading 000000**.app files for Sneek and MyMenuify
Provides solutions for the upside-down homebrew channel and the HackMii installer No Vulnerable IOS problems
Advanced Custom Downloads Feature will allow you to easily patch and change the slot/version of IOSs/cIOSs (only use this feature if you know what you are doing!!)
How to Use ModMii
Download ModMii
Extract "ModMii#.#.#.zip" to the directory of your choosing
Run the "ModMii.exe" file by double-clicking it (if it doesn't work right away, you may need to right-click it and select run as administrator, also make sure your firewall or proxy is not blocking the program from accessing the internet)
Choose an activity from the list on the Main Menu to begin (see screenshot below for options). Note, a custom guide will only be generated when "ModMii Wizard (W)", "HackMii Solutions (H)" or "USB-Loader Setup (USB)" are selected.
How to mod your Wii
Run ModMii, from the Main Menu enter "W" to start the ModMii Wizard
When asked if your Wii is a virgin, you can answer yes "Y" even if your Wii is not a virgin in order to re-hack your Wii and update all your Wii's softmods. You should only answer no "N" if you know specifically what softmods need updating or if you only want to change your system menu version.
Answer the questions ModMii asks about your Wii, it's very simple, so I won't even go into the details, but here's a video tutorial made by Pepxl based on v4.0.1. Later versions work much in the same way, so its still a great tutorial even if you are using a newer version.
Wait until the program is done working, verify that all the files downloaded successfully, then (if you didn't change the drive letter to your SD card) locate the newly created folder called "COPY_TO_SD". Copy everything inside this folder to the root of your SD card (merge folders if it asks).
Now just follow the generated guide.
And if you set up the SD card correctly afterwards (just put the basic loaders etc on it) there is no chance of your younger siblings f*ing up your Wii.