To start a salt water pool you will need a salt generator/salt cell which has a unit that is plumbed into your swimming pool system, and a power source for the cell. You would then follow the manufacturer’s directions to add salt to your pool until the residual salt level was at typically 2700-3400ppm in your pool. For a typical 25,000 gallon pool this would most likely be between 14-18 40lb bags of salt.
You do not need to remove the chlorine from your pool, as your new system will also be generating chlorine. (which was one answer that I saw on a discussion board).
Also, salt water is much more saline than a salt water pool, so you would not use salt water from the ocean to start your system. Just in case you were wondering.