What kind of high school classes do I need to take to het in to a computer tech school?

Alexander the field of study is Computer Science. The study of computers is important background information needed for computer jobs, even though you may be considered an expert user of peripheral compute devices(Gaming and Hand Held devices). Being familiar with how a computer operates and what is physically required to make a computer function is good knowledge to have when going into the tech field. Becoming a field technician is as varied as to what you need to know, as the type and number of compute devices that are in use today. Many of the jobs will train you, if you have applicable skills. So if you have a good idea of what you would like to support in the field, it would be good for you to learn as much about the product/device/system as you can from reading and discussing with others who are knowledgeable on the subject.

If offered as a class "Intro to computer Science" should help to understand the function and history of computing.

Any class on operating systems or computer I/O programming are good areas to investigate.