Seeing that you are new, I will catch you up to speed:
Homebrew with CIA's are only available with version 9.2 as it has a kernel exploit for ARM9, meaning you have "full" access to the system. People who have already updated to higher systems are out of luck...EXCEPT!!! If you are on version 10.3 or below. You can get sysUpdater, a program, to downgrade your sysNAND to 9.2. Therefore, you will have access to a plethora of hackable's: such as Custom firmware, emuNAND, homebrew on the Home Menu (CIA's), etc.
To simplify the difference between emuNAND and sysNAND:
sysNAND is your 3DS system's NAND memory: it contains all of the vital system files and information such as the firmware and boot-up information. It is located on your 3DS's motherboard. EmuNAND is basically an emulated version of the sysNAND ( kinda like playing a game on an emulator rather than the actual system), which is located on a hidden partition of your SD card. With emuNAND installed, your 3DS bow has two options- to boot from sysNAND or emuNAND. Therefore, you can have two completely different firmware versions on your system.
But, you have 10.5, which has patched it
:/