Some people take a longer method of doing it by clicking the New Order icon but for me I set the pending order directly from the charts because its faster and saves time.
I will give an example of how to place a Pending Sell Order on an MT5 BTC/USD chart.
Step 1
I right-click on the price I want to target.
Note that to open a Pending Sell Order you right-click above the current price and to set a pending Buy Order, you right-click below the current price.
The idea is to buy when the price is low & sell when the price is high.