Homebrewing is the process of using various exploits to allow your device to run custom software, this can include games, emulators, and various tools. There are a wide variety of ways to homebrew your 3DS, but for this Instructable we will be using Browserhax, an exploit using the Nintendo 3DS's internet browser. This is a fairly simple and quick process that just about anyone can accomplish that works on all versions of the 3DS, including the 2DS.
Step 1: Determine If Your 3DS Is Capable of Being Homebrewed
The firmware is the operating system that the 3DS runs on. Firmware is updated as time goes on just like any major product, with higher numbers being newer versions. The firmware version of your 3DS can easily be determined by selecting the System Settings icon and checking the bottom-right corner of the top screen. Currently in order to use Browserhax your firmware must be lower than 10.3.0-28. However, starting with version 9.9 the firmware will check if the system is up to date, and if not, refuse to allow you to use the browser. If you see the nag message you will not be able to use Browserhax, but it is possible to circumvent the nag message by performing the following steps:
1.Go to System Settings and change the date to January 1, 2000, 00:00.
2.Use the browser 'Initialize save data' option, before any page gets loaded triggering the browser version message.(Note that you can't press the HOME button to return from the browser, otherwise you will have to re-initialize the save data again. Once the date reaches January 2 you will need to perform these steps again in order to use this workaround.
In the bottom picture you can see three examples of the firmware version. As you can see the red New3DS is not capable of being homebrewed, while the black 3DS XL and black original 3DS are.
Step 2: Prepare Your SD Card
In order for Browserhax to work properly, we must first prepare the SD card that we are using with our 3DS. Remove the SD card from your 3DS and plug it into your computer. All that is required is to download the latest homebrew starter kit, (which can be found here), and simply extract everything from the file to the SD card your 3DS will be using. Make sure to place the files in the root of your SD card, which is the main section that opens up when you open the card on your computer. Once the files are installed, return the SD card to the SD card slot on your 3DS. Different 3DS models have the slot in different locations, so make sure you know where to find yours.
Step 3: Access the Launcher
Now that we've prepared our SD card we can utilize Browserhax on our system. Navigate to the 3DS web browser, which can be found at the top of the bottom screen when in the main menu, and either type in this url (http://yls8.mtheall.com/3dsbrowserhax_auto.php) or you can use the 3DS's camera, which can be activated by pressing both the L and R buttons while in the main menu, to scan this qr code which will automatically direct you to the webpage. If we have set everything up correctly, we'll see the bottom screen flash several different colors and eventually the top screen will turn black with some white text appearing momentarily. We will then be greeted by the homebrew launcher menu, with several pieces of software already installed for us to play with.
If you are stuck in the screen flashing part for more than 30 seconds the installation has failed and you will need to turn off your system and try again. If you the installation continues to fail, try deleting the browser's cookies and history. This can be done by accessing the "Settings" button in the web browser. And be patient, it sometimes takes several attempts for the installation to be successful.
Step 4: Configure Menuhax
This is an optional step but unless you want to go through the browser every time you want to access the homebrew launcher you might want to set up Menuhax. This application allows you to set up a button or multiple buttons to hold down while you turn on your system that will boot the launcher for you.
Go to the Menuhax Manager in the homebrew launcher. Once it loads, select the "Install" option and follow the steps the application provides you. By default Menuhax is set to be activated while holding L + Down while the system is turning on, but you can change this in "Configure/check haxx trigger button(s)".
Step 5: Have Fun!
Now that you have successfully homebrewed your 3DS, you are free to install and play with a wide variety of community-made applications. I've attached pictures of just a few to give you an idea. A list with several different applications can be found here. Make sure you place the files in the "3ds" folder when installing.
I hope this Instructable was helpful, please let me know any feedback you have and thanks for reading.