I am extremely new to algo coding. Also new relatively new to Python. NOT new to programming (8 years on and off).

This is what I have in Initalize:

self.SetStartDate(2017, 4, 1) # Set Start Date
self.SetEndDate(2020, 4, 1)
self.SetCash(100000) # Set Strategy Cash
self.es = self.AddFuture("ES", Resolution.Minute)
self.es.SetFilter(10, 90)
self.myema = ExponentialMovingAverage(200)
self.RegisterIndicator(self.es.Symbol, self.myema, timedelta(minutes=5))

This is how the docs said to create an EMA and consolidate to 5 mins? Doubt its correct (because of me)

myema.IsReady() always returns false in OnData 

when I said "Price" in title: I am confused for backtesting what price would be used to determine a cross of an EMA, Because my understanding is there is no "Last" data logged in previous market data?

Just wondering if someone can start me off. I have absolutely no traction and I've been staring at the docs for 3+ hours