Can anyone help me understand the stock market and its working?

GDP = Gross Domestic Product. Essentially it's the total value of all goods and services produced in a country.

I'm not sure what 18k and 19k points are. In stocks, points generally equate to the value of a stock in dollars. If a stock goes up by 18 points, it goes up $18 per share. If the Dow Jones index (a group of 30 stocks) goes up 100 points, that means the value of that group of stocks went up $100.

Not really sure of a specific source for info like this. Maybe go to the library and pick up a Stocks for Dummies book or something similar.

The stock market is basically an auction were you have people buying and selling stocks. It is made up of different exchanges like the NYSE and NASDAQ, companies sell stocks in their companies to generate additional income so they can build up their businesses. Investors are made up of institutions all the way down to individuals. They buy and sell stock from long term to short term, depending on their objective. The numbers you see on the screen is an average that investors can use to gage the direction of the market, it will change second by second as the trading day progresses. The guys you see on TV yelling at each other are the specialist at the NYSE, they still control the stocks in that exchange. The NASDAQ is all computerized, so it is instant and quite. For more information go to HOW STUFF WORKS.com and go into money.

The stock market is quite a complex subject, and not easy to understand. Try some of the stock exchange web sites. Some of them offer advise and give basic tutorials about trading stock. Also some stockbrokers' web sites can be helpfull