Steveice10 proposes the 1.4.6 version of "FBI" open source utility for the Nintendo 2DS / 3DS for installing the CIA files.
The CIA files are chains that may contain 3DS Games / Applications / Games Eshop / Homebrew / etc ... who settle in the system menu of the console. For comparison, the CIA files for the Nintendo 3DS what the WAD files for the Nintendo Wii. The application is accompanied by another "utility sockfile" that allows sending files to the FBI CIA utility via an internet connection.