A moving average is calculated by adding the prices for a predetermined number of days and then dividing by the number of days. (gffbrokers.com)
The next data point would drop the earliest price, add the price on day 11 and take the average, and so on as shown below. (investopedia.com)
I don't recommend pure price action trading, but I have found that adding price action techniques to a profitable trading system can be very powerful. (fxdayjob.com)