On technically on how to build an EA, there are 2 options that I know:

  1. learn to code
  2. Use the ea that it is already build-in every indicators, you just have to put condition if-then and it automate run on the past for you to test. If you satisfy then save it for future use. Many broker now offer this options.

But bear in mind, no ea going to pass thru market without constance monitoring