Blue Line with candle is 21 Moving Average which is also acting as a good support to BTC, Look at MACD indicator down below...
Line 1: BLUE- MACD Line(12) Line 2: ORANGE- Signal Line(26)
lines are 12&26 MA
CASE1: When Orange Line Crosses Blue ....Orange Down and Blue UP...Market will be GREEN CASE2:Whenever Blue line tries to Cross Orange line and Cross it...BLUE Down and Orange UP.....Market will be RED
The best time frame for the MACD does not exist. This would be completely up to your personal preference; however, daily signals (1D timeframe) are more significant than shorter.