Then learn the basics of analog electronics, figure out the transistor, the basic principles of the field effect tube and the basic circuit;
Then learn the basics of digital electronics, figure out the basic principles of digital circuits. Then come back and analyze those circuit diagrams!
You can try while learning, your school may have an oscilloscope, multimeter or something to buy their own on the line, learn the basics of circuit analysis, you can go to the electronics market to buy their own resistors, capacitors, inductors, circuit boards, soldering irons, soldering and other devices and tools, do some experiments, in accordance with the book of circuit diagrams to build soldering, power on the oscilloscope to see if the signal is the book as said.
In fact, this knowledge, college and then learn it is not too late, since they are now interested in, it is possible to take a step forward. It doesn't affect your high school studies.