DSX operates on a Maker-Taker fee structure.
Maker fees are lower because Makers provide liquidity to the order book. Makers place orders that are lately used to fill counter-orders of other traders. To encourage provision of better liquidity, maker fees are generally lower.
Takers consumes the liquidity by "taking out" provided offer placed by Makers.
Basically, you become taker if you are placing an order that is being immediately filled. Maker's order will be placed into the order book and doesn't get filled immediately. It is active until someone fills with it.
Market orders are always considered Takers, since market orders never go on the order book.
Trading fee is paid after the trade is executed. Upon the filling of your order it gets defined as Maker or Taker and the according fee is charged from the amount you receive as a result of the trade.