A promoter establishes a company by preparing important documents like the memorandum of association and articles of association. The promoter investigates the business idea, arranges financing, and incorporates the company by registering it with the registrar of companies. Key documents that must be filed include the memorandum of association, articles of association, and documents related to the directors and initial shareholders. Once incorporated, a public company must obtain a certificate of commencement of business before beginning operations.