In order to form a private limited company, one or more shares must be issued, set out in a 'statement of capital' and normally distributed amongst directors and investors.
It is for the founders to decide on how many total shares should be issued. However, when issuing shares to founders, you should consider the total number of shares you want to issue. For example, where there are 4 founders and 1,000 shares are to be issued, the number of shares issued to each individual founder should not exceed 1,000 shares (ie the total number of shares) when added together.
For more information on shares, read Types of shares.