USBLoaders display the content of the GameID.txt file. The gct is not displayed by loaders. But if you correctly generated the .gct file and placed it to the correct place, with the correct name, you only need to enable the Ocarina option in the loader to use it. You don't need to display its content. The gct is the data which is loaded by the USBLoaders to patch the game content. The txt is a list of ALL game's codes possible to enable. This list is displayed in the loader for you to select the code you want or don't want, then generate the .gct from the enabled codes. Gamecube games already have few cheats listed on geckocodes.org. You can download these lists directly from the loader, then display the codes you want to enable and generate the gct automatically. The tutorial on the first post is only for cheat codes you find elsewhere, not included in geckocodes website.