Okay here is what I did.My game has already been saved to a memory card.
I followed the instructions in the manual.Then I put the gameshark thing in the slot above the first controller.Then I put my megamemory memory card {that i saved final fantasy x to last week}, and I turned it on.Then I pressed the open button, and inserted the disc that came with it.After that, I went to gameshark codes, then I clicked add new game title.I entered the title Final Fantasy X, and the slot below that I entered a code from here
https://www.rpgplanet.com/ff9/ff10/ and clicked done on the little keyboard.When I clicked done it came to another screen, and there, I pushed the circle button to go to the code I put in.I did that for all of them, accept for the ones that had more than one code.Then I clicked Start, and did the game thing, I took out the disc and put in Final Fantasy X, and left the gameshark thing in the slot.Do I have to do the game all over again, or did I do something wrong?