Trade stocks, accumulate cash to trade better stocks, and become a millionaire but watch out, if the stock is red and going down you'll lose money. Only trade stocks in the green. Hire managers or brokers to trade stocks for you, they never lose money but they're slower than clicking. Unlock achievements to earn gold and use it for upgrades and other unlockables.

Trade stock on "stocks" page
Click "research" to trade that stock with more money.
Hire managers to trade for you on "brokers" page
Unlock upgrades and more under "premium"