I'll save you time and recommend against starting a company if you're having to ask these sorts of questions... you'd lose money and it'd generally be a waste of your time. Try joining one first... you'd probably actually do better as an employee than you would as a director.
If you go to the company page itself though
http://www.torn.com/joblist.php#/p=corp&ID=3 and hover your mouse over each company position (For any company) it will tell you what they do for the company.
The stock for a flower company? Well... I'd have thought that one was fairly self explanatory, but either way is irrelevant as you're not buying physical items to sell, in a company it's all self contained... you order/create 'stock' in companies and sell it at the same time, you never have any physical items, just numbers and money. You decide how man you want to get shipped to your company and what prices you wish to resell them at. Or alternatively in some companies you are required to create the product/service and you decide what price you distribute that at (e.g. in oil rigs, you create the barrels of oil then sell them)