I am sure there are instructions that come with the Zerostat, but I have had mine for at least 20 years and have no idea where they might be. I also have seldom used the Zerostat as both Texas and Florida are very humid and little if any static electricity.
As I recall, however, I put the record on the turntable and held the Zerostat at the far side from the tonearm at about two inches from the record. This was when I live on Long Island.
I must say that I recent heard the benefits of the Walker Talisman magnet on my records. Static electricity or not, it greatly improved the clarity of the lps. It is a new product from Walker Audio. I also found my Zerostat and tried it once again. It did nothing.