One of the best books I ever read, and one that really set me on the right path when I was young was Rich Dad Poor Dad.
I haven't read it in probably a decade or more, but I remember this having a big influence on not only my investing habits, but spending/saving as well.
Another really good author you need to look at for a younger person is Peter Lynch. His books are very easy to understand, yet pack the same amount of useful information as a author like Benjamin Graham, who although is the best investor of all time arguably, is insanely hard to read. I remember when I was first starting out, Intelligent Investor was very, very hard to get through.
Got to remember, introducing one to the stock market doesn't do much in and of itself. I know plenty of people who were introduced to the markets, and quite frankly they are very poor investors. They chase quick gains, and most have ended up with very quick losses. Understanding the value of money, correct saving habits and patience in the markets is infinitely more important.