1 - Download these files:
https://www.mediafire.com/?gfkbqbsem0j4bi7
2 - Unzip the archives using your favorite program.
3 – Locate on the folders you just unzipped the files for “arcode.bin”.
4 – Copy “arcode.bin” to the root of your SD card.
5 – To use a code already found you must open the “ar2bin.exe” (found in the contents of first link downloaded and unzipped), type in the codes, from the desired game, in the program and click “save”.
6 – Save the file on the root of your SD card, with the name “arcode.cht”
7 – Place your SD card in your 3ds, turn it on, and start the game you got the codes.
8 – In middle game press the “home button” on your 3ds.
9 - Open the browser (WITHOUT CLOSING THE GAME!) and open this site
http://bit.ly/1LgLvSG (bookmark it for a faster process).
10 – It will load the code, and after a very few seconds* the browser will close and an error message will appear saying: “An error has occurred. Please save your data in any software currently in use, and then restart the system.” (IT´S OK, it is supposed to do that!)
11 – Press “OK” and go back to your game. The code should have been applied.
12 - ???
13 – Profit.
* While the code is loading you may think it froze the 3ds, but usually it didn’t, look for the clock and see if the “:” is flashing, if it stopped for more than 30s, then yes it froze, try again!