The first step toward answering your question is to determine what your interests/talents are.
Video game development careers typically fall into one of these several categories:
There are also several business-oriented positions within game development companies.
So, what are you most interested in? Art careers, like a character artist or environment artist, require someone with excellent traditional drawing ability and an education in fine art or game art, with additional training in the use of standard software like Maya, ZBrush, 3D Studio Max, and Photoshop.
Programmers write code and develop software tools, and should have an education in game development/design, computer science, and advanced mathematics. In fact, programming requires a lot of math. You must also learn to master scripting languages like C/C++, Lua, Python, Java, and others.
Animators, and those that work closely with them, like character riggers, must be trained in the use of animation software, and should have an education in computer animation and art.
Designers are like jacks of all trades, they usually have considerable talents in art, animation, programming, etc.
There are dozens of different jobs within game development studios, so you may want to look through this site: http://getinmedia.com/industry/games
On that page you will find a list of careers with links to profiles that talk about the duties of each career, the skills/education required, and what to expect. There are also employer profiles that discuss what it is like working at various game companies.
So, once you have decided which specific area you are interested in, then you can determine what type of education you will need. While you are in high school, you can try to take classes like art, computer science, etc. These can help prepare you for college, and give you a good foundation of basic skills.