Managing your Investments
From here, you can buy and sell shares of businesses as you wish. Select the store which you would like to buy or sell stocks of, the amount you would like to buy or sell, and then hit buy if you would like to buy, and sell if you would like to sell.
Investing, of course, can be summed up by: "Get lots of money!" But there's a bit more to it than that. Look at the record of who's running the store. Do they look like they can make it a successful, profitable business? There is a risk to everything - that the store may shut down, and you lose all your money. But there's also a chance that you'll make hundreds or thousands of dollars just by deciding wisely from the start.
Of course, if you are filthy rich beyond belief, and don't know what to do with your money, risk is less of a problem (unless you intend to keep all your money until the end of time). Investing is also about getting to things early - if you can buy at the beginning, confident that it will grow to be an exceedingly profitable business, by all means, invest invest! Others, who didn't buy stock initially, may do so if the store goes into a slump, trying to beat out a competitor or trying to get by.