Insert the MicroSD into the Action Replay cartridge; then insert the Action Replay cartridge into the DS. Insert the game with the saves you want to back up into the Action Replay's slot. Turn the DS on, and then select the option to back up the game.
"Dragon Quest IX: Legend of the Starry Skies" is the latest Dragon Quest game, released in 2010 in the US for the Nintendo DS. The DQIX Save Editor is a fan-developed program that can hex-edit a huge amount of variables in the game, from party member appearances to equipment, armor and weapons. Typically, these altered save states are played in emulators but can be transferred back to the handheld to play on the DS.
Enter the name of the game, and then select "OK" on the onscreen keyboard to back up the saves. Connect your Action Replay DSi to your PC with USB, or insert the MicroSD card into a card reader. Open the DS save converter, and then select the file from Windows Explorer. Convert from .duc into .sav.
Open the *.sav file in DQIX Save Editor, and make the changes you wish to your savegame, which are represented and explained clearly in the editor. Load this *.sav in an emulator to test to see if your changes were made.