The long line candlestick pattern contains one candlestick, and it is found by identifying a candle that has a body with no wicks. This is an indication that the market opened and pushed as high as it could without pulling back or opened high and fell as low as it could for that given period. No wicks indicate that the market had very strong opinions for that given period.
To complement this candlestick pattern, look at volume. Volume is a very useful tool in helping to identify if the market is truly moving or if it is a fake out. The more people behind a market move is typically better. Beyond that, find other tools that complement this pattern and begin to study it. Again, this is one of the easier candlestick patterns to identify and it can certainly up your trading game.