Trading with "play" money is like playing poker with match sticks. It's not the same as with real money. I suggest buying 2000 shares of a penny stock like ACII or 5000 shares of ITRO for a taste of the real thing.
When the company initially sold the stock, it financed the company. Those who bought the stock became share owners of the company, as you do when you buy stock. The market value of a compnay's stock determines the value of the company, which directly and indirectly affects the company's ability to finance its operations. So, yes, when you buy a stock, you are involved in the success of a company
How would investing in Exxon be a double edged sword? As a share owner, would you not be lining your own pockets by buying their product?