You can become a chairman either by appointment or by vote of either the body over which the chairman will preside or an outside person or committee that is authorized to make selections. Many types of organizations appoint a chairman to head operations, but a chairmanship in the corporate context is the most likely to provide a career path and payment for services. Every corporation has a board of directors and a chairman that presides over the board.
A chairman presides over a body of members, serving as the organizer and final arbiter of disputes amongst the group. Corporate boards of directors ordinarily have a chairman that can be either an executive or a non-executive of the corporation. In the US, it is common for the chairman of the board to also be an executive of the company under the chief executive officer (CEO) title, while in the UK, it is more common for the chairman of the board to be a non-executive.
To become a chairman of a board of directors in an executive capacity, you have to be qualified to run the company. Unless you own the company and control most of the stock and can appoint yourself to the position, you have to develop the credentials to be hired as the most senior executive of a corporation. The larger the corporation, the more stringent the hiring requirements are.
Executive-level positions typically require an undergraduate degree in a business and possibly a master's degree in business administration or a related degree, such as in law. You will often work your way up from an entry level position to a management position to an executive position. Some corporations have executive training programs that will put you directly into an executive level position upon completion.
You can also become a chairman by making a lateral move. If you have the education and enough experience in one corporation, you can apply to another corporation to fill a CEO vacancy. The level of difficulty in getting hired by any corporation is dependent upon the size of its operations. It is easier to move up in a smaller corporation, and that can be a steppingstone for a lateral move to a larger company.
Boards that use a non-executive model select board members and board chairs from outside the company. To become a chairman on this type of board, you will likely have to be a recognized professional in your field. Some larger public corporations elect board members by vote of the shareholders. In this case, to become a chairman you would first have to get on the ballot and get elected to the board. Then, you would have to convince the board to appoint you as chairman.