How to invest money in some kind of stock?

If you have a limited amount to invest the best place to go is Sharebuilders. They allow you to buy stock every month for whatever set amount you want to invest. The money is taken out of your account every month and invested in whatever stock you designate. You can invest as little or as much as you want to each month and it's all done online.
Check it out on the Internet.

Investing in single stock is risky. You can minimise the risk by diversifying and investing in stocks whose returns are not corelated.ie; if you pick a stock that goes up with the market also pick a stock that goes against the market. You create a portfolio of such stocks that are non corelated and you have well diversified portfolio where you can tailor make the risk and return you require.
Suppose if you pick a stock which has a risk of x and return of y and allocate 'a' portion of your investment corpus to it then your risk will be a times x. Similarly you choose other non correlated stocks and related stocks as a portfolio with risk and return calculated to yield your prefered return and risk.

First lesson would be NOT to invest anything in the stock market until you learn how it works. Investing in stocks is very tricky especially individual stocks. Anyone who tells you it is a piece of cake to earn money trading stocks is lying. It takes a lot of practice and knowledge.

The websites listed below should get you started down the right path.

first make sure you want to INVEST, not SPECULATE.

once decided, if your answer is to SPECULATE, then i have no clue for you.

and if you really want to INVEST, then its not a type of question you should have just asked on a forum.

go and read books, research on stock market, research on the history of stock market, major rises and falls, reasons, future political international affairs, economic prospect of regions, natural recourses of the country you want to invest in, gold reserves, oil reserves, dollar reserves, .......and so on......

and if you decide a business which you think you know very well, then get the list of companies in it, research on them individually.......SPECIALLY ON THE P/E:

by P/E i mean when u have really decided that you are going to in vest in a company, after going through all of the above stages, at that stage get the company's at least past 7 years P/E, gets its ratio, that is 7years P/E figures divided by 7, then multiply it by 25, if the P/E Ratio comes out to be larger that the once mentioned at present, be carefully in investing in that company as its stocks are expensive...and if its lower then the stocks are cheaper...........