This is a business where your are asked to send money, a nice round figure that won't break the bank, say £10. This is given to a person who is placed at the top of a list of other people, usually about 6.
Then your details are added to the bottom of this list and copies are sent to a couple of hundred selected people, randomly selected.
If you find yourself involved in a chain letter business you will be entering into a vocation that is more than likely to cost you dearly in time, effort and money. You will not earn from the scheme. The advice here is quite simply to kick this business into touch!