How to maintain safe investment and earn from stock market?

in other word. is it possible to have your cake (capital base) and eat (earn out of it more then regular ) it too?

The basic answer is no. There is no totally safe investment. Generally speaking, the less risk you're willing to assume, the lower the reward you can expect. If you think of low risk as beginning with a bank savings account, you can make about 3% right now. Six years ago, these vehicles paid only about 0.75%. As interest rates have risen, they've gone up with them.
The next step up would be CD's and government bonds. CD's are FDIC insured, and pay somewhere around 4.9% to 5.3% right now. Government bonds are backed by the full faith & credit of the US government, and pay something close to the CD rates, depending on the length of time they represent. All of the foregoing investments are pretty safe, and pretty tame in terms of returns.
The next group of investments consists of stocks. These are certificates of ownership in various US and some foreign companies. By assuming ownership, you subject your money to the fortunes of the companies you own, so the risk is no longer guaranteed, and if your company loses money, so do you. Likewise, if they are successful, you are too!
Contrary to what some of your respondents have said, it IS possible to invest without spending a fortune with unscrupulous brokers. The most important step to take is to educate yourself about investing before you begin, so that you know what questions to ask. I know some wonderful people in the brokerage business. I also know some dishonest ones, and all the greedy ones in between.
The business of investing takes a lot of time and a lot of education. You either decide to educate yourself, or you pay someone who does it for you.
Also, the Dow is an index of only 30 large US industries, and although it's widely regarded as an indicator of "the market," the Nasdaq, representing a multitude of companies of many sizes and types, weighted by their capital, is a much better indicator of what the businesses of this country are doing.