How do I place a pending order on MT4?

A pending order is an instruction to open a position when an instrument reaches a certain price pre-defined by you.
You can place a pending order via the main ‘Order’ window. Simply change the ‘Type’ from ‘Market Execution’ to ‘Pending Order’. A drop-down menu will then appear that will allow you to specify whether the pending order you are about to place is a Buy Limit, Sell Limit, Buy Stop, or a Sell Stop Order. It will also allow you to set a limit price and expiry date and time.

Bear in mind that Buy stops & Sell limits must be placed above the current market price while Sell stops and Buy limits must be placed below the current market price.