Mauzer
shared author's Samuel Olowoyo article
The Use of the MQL5 Standard Trade Class libraries in writing an Expert Advisor 
This article explains how to use the major functionalities of the MQL5 Standard Library Trade Classes in writing Expert Advisors which implements position closing and modifying, pending order placing and deletion and verifying of Margin before placing a trade. We have also demonstrated how Trade classes can be used to obtain order and deal details.