The Software
While the Action Replay DS ships with a number of cheat codes pre-installed, eventually you will probably want to get new ones or design your own, so start by inserting the included CD into your Windows PC and installing the Action Replay Code Manager.
Updating Codes
Keep your code database updated by clicking on the DS cartridge in the upper-right corner of the window labeled "Software Upgrade."
Selecting Your Codes
The left window is your list of codes, arranged by game title in the left window. Drag and drop the titles of your games to the list in the window on the right labeled "Subscriptions." From there, you will be able to browse the dozens or even hundreds of cheats available for each game.
Common Uses of Codes
The most common features accessed via Action Replay cartridges include unlimited use of special abilities, unlimited lives, unlocking of high-level items, an unlimited timer for time-trial games and immunity to damage. Each game will have its available cheats clearly listed.