cAlgo coding for MACD bot

Hi,

Can someone tell me how to start learning the cAlgo coding? I want to try and build a basic MACD crossover algo that buys when MACD crosses above signal line and sells when MACD crosses below the signal line.

I tried this one below but it has a problem that it only buys when the MACD crosses above zero line and sells when it crosses below zero line and by that time it is too late to open the position.

using cAlgo.API;
using cAlgo.API.Indicators;

namespace cAlgo.Robots
{
    [Robot(AccessRights = AccessRights.None)]
    public class MacdBot : Robot
    {
        private MacdHistogram _macd;
        private Position _position;

        [Parameter(DefaultValue = 10000, MinValue = 0)]
        public int Volume { get; set; }

        [Parameter("Period", DefaultValue = 9)]
        public int Period { get; set; }

        [Parameter("Long Cycle", DefaultValue = 26)]
        public int LongCycle { get; set; }

        [Parameter("Short Cycle", DefaultValue = 12)]
        public int ShortCycle { get; set; }

        protected override void OnStart()
        {
            _macd = Indicators.MacdHistogram(LongCycle, ShortCycle, Period);
        }

        protected override void OnBar()
        {
            if (Trade.IsExecuting)
                return;

            bool isLongPositionOpen = _position != null && _position.TradeType == TradeType.Buy;
            bool isShortPositionOpen = _position != null && _position.TradeType == TradeType.Sell;

            if (_macd.Histogram.LastValue > 0.0 && _macd.Signal.IsRising() && !isLongPositionOpen)
            {
                ClosePosition();
                Buy();
            }

            if (_macd.Histogram.LastValue < 0.0 && _macd.Signal.IsFalling() && !isShortPositionOpen)
            {
                ClosePosition();
                Sell();
            }
        }
        private void ClosePosition()
        {
            if (_position != null)
            {
                Trade.Close(_position);
                _position = null;
            }
        }

        private void Buy()
        {
            Trade.CreateBuyMarketOrder(Symbol, Volume);
        }

        private void Sell()
        {
            Trade.CreateSellMarketOrder(Symbol, Volume);
        }

        protected override void OnPositionOpened(Position openedPosition)
        {
            _position = openedPosition;
        }

    }
}