hello firemaker,
this file contains 1000 circuits that you can build and test your self .
it has tons of circuits about :
Audio Circuits
Consumer Circuits
Display
General Electronics
Measurement and Sensor Electronics
Power and Battery Circuits
Radio Circuits
Signal Generation
Electronics circuit is a bit big category.
Try to focus on transistor circuitry and opamp circuitry first. They are all fundamental and will help alot in your learning