Poloniex trading margin

A few nights ago, I saw my friend (@steemvest17) who traded margin on poloniex.com. Since it was new to me, I asked for a little explanation for him about the trading margin. Here's is the explanation I got:

1. What coins can we use for trading margin?
   the trading margin feature in poloniex is not available for all coins, only certain coins that we can use for trading margin. The coins are [STR, ETH, BTS, XRP, XMR, LTC, MAID, DOGE, DASH, FCT, CLAM].

2. What is the difference between trading margin and exchange?
   Between exchange and the trading margin is very much different, in exchange we only exchange the coins we have with other coins available in the market. while trading margin the number of coins that we have will be doubled by poloniex, which means if the market value in accordance with what we predict then we will get multiple benefits.

3. How to trade margin?
   This is a difficult question to answer, if you just want to know the basic way, then the short answer is to move the balance that is in your balance exchange to balance trading margin, then do the purchase or sale as usual.