Instead of directly answering the many questions available on the link, I will provide you with information that will help you solve them.
There are a number of energy sources available to mankind. Some of them are renewable, others non-renewable. Renewable options, such as hydroelectricity, solar energy, wind energy, geothermal energy, wave energy, etc. are regenerated and thus are inexhaustible. Non-renewable options, such as coal, wood, natural gas, etc. cannot be regenerated and once used up will be exhausted. Coal and natural gas are also known as fossil fuels because they are fossils of decay products of life forms (plants, animals, etc.).
For the production of electricity, we generally depend on the combustion of fossil fuels to generate power at very high voltages. These high voltages are brought down to a few kVs (kilovolts) in substations and finally transferred to our homes at 220 or 230 volts (or the prevalent voltage, say 110 V in US). The transmission takes place through transmission lines.
Hope this helps.