what paper work do i need to do a short sale?

Answer 1

You mean the book entries,
You credit your margin and the sum beyond margin which is the price of stock - margin. You debit the price of stock.
Scenario 1 the stock price moves up
You increase the margin payment in the credit column which is a margin call. The price beyond the margine in the stock - margin again as above.
Debit the addition to the stock price.
Scenario 2 the stock price moves down.
Margin is credited and Stock - Margin is credited.
New Stock price is debited and extra cash formed is debited as asset to the buyer.