To get the magic, you go to the Autopia Quest Track in Tomorrowland and go over to the "ATMs" as some people call them. They are to the left of the tubes on the right-hand side. There are 4 different quests for 4 different cars. It used to go in order of difficulty, but now the order you should do the quests is Quest #1, then 3, then 2, then 4.
There are spoilers on here somewhere. Do a search for "Autopia" or "Lights, Cameras, Engines".
There's a section in tomorrowland called the shipwreck graveyard. You just need to go there (I hope you have diving magic, though, because you're going to need it).