can an employee buy stock from the company he/she works for?

Yes, and the company would love it if you did but it isn't always the wisest thing to do. If the company went belly up, both your job and your investments would be at risk. The people at Enron found this out the hard way.

You have to have access to inside information or have decisions authorities that are critical to the business to be an inside trader. Unless you're an important high level executive, you won't be considered an inside trader.

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The good news about penny stocks is that you can buy a good amount of shares without going broke. It’s thus easier to get a good stake in a company for less than you would pay for stock of a larger organization. To find a company that you feel confident investing in, make sure to do your research. Don’t just choose a company because you saw an article about it, or because your friend is investing in it.

It depends on your position. If you are a director or even senior management you will have to ask your CEO. If you have inside information and then trade you will be commiting a criminal offence. Directors may not trade in close periods.

Otherwise there is no reason why an employee may not buy shares in his own company.

every body can buy the stocks if is a public company

Yes, you can, as long as you're not a very large shareholder. Even if you overheard a rumor and traded based on that, nobody would have reason to accuse you, since people are buying and selling every day for many reasons.

normally u can buy it .

normally not from company directly.

not enough info for - "insider trading".