Pick up your metal basket and turn it upside down, looking closely at the holes in between the wires. Check to see that they are big enough for the plug end of the extension cord to go through them but small enough that the rocks will not fall through.
Push the plug of the socket extension through the wire basked from the top. Pull it all the way through, so that the socket end sits inside the basket.
Pile the rock salt around the light bulb in the basket. Cover the bulb with salt nearby. The heat from the bulb will release the negative ions in the salt. Be careful not to break the bulb.
Place the basket on a table, and plug in the socket. As they heat up, the rocks will begin to add negative ions to the air.