What's the use of shares in small companies that are not listed?

Shares can be distributed or sold as dividends. But is there a specific contract? To what extent do you give shares? how much is it? What if it develops well in the future? So there must be legal procedures, contracts and vouchers. How is the company? Is there room for development? Will the company pay dividends in proportion to its shares every year? You have to think clearly. In fact, it is more important to exercise personal ability, learn things and accumulate experience than salary and shares. I hope to adopt.