How do individuals buy company equity?

I need to bring my ID card to the business hall of a securities company to go through the relevant formalities, then download the market trading software of a securities company with an account and install it on the computer and mobile phone, and transfer the funds deposited in the bank to the securities account for trading. Equity investment is the act of investing in and purchasing the equity of a company in order to participate in or control its business activities. It can occur in the publicly traded market, when a company is initiated or established, and when shares are transferred privately.