Working of Resistance

Well first you should learn basic circuit network theory. This will teach you how to apply Kirchoff's circuit laws. Next you should learn about the Shockley diode equation. This should now show you that the very non-linear nature of a diode will mean that a slight change in the voltage drop across a diode will mean a very large change in current drawn. Excessive current will release the inherent smoke trapped inside the LED. Now to understand how the inherent smoke produces the above diode equation for voltage and current and how the LED converts current into light will require an understanding in quantum mechanics.