The Evening Star is multiple candlestick pattern which is formed after the uptrend indicating bearish reversal.
It is made of 3 candlesticks, first being a bullish candle, second a doji and third being a bearish candle.
The first candle shows the continuation of the uptrend, the second candle being a doji indicates indecision in the market, and the third bearish candle shows that the bears are back in the market and reversal is going to take place.
The second candle should be completely out of the real bodies of first and third candle.