There are lots of learning pages on Stockcharts, check out the "Chart School" tab on the main home page, then go to "Chart Analysis" and then select one of the pages on candlesticks. the link below will take you right to this page, but look around there are lots of different subjects.
I would also recommend any books by Steve Nison or Greg Morris.
Basically the colours can change depending on which colour scheme you select to generate your chart in. Standard basic candles are hollow or filled, so in a black and white chart they are white boxes with thin black outline or a solid black (or red) box, indicating a close higher than the open or a close lower than the open. Now in some other colour schemes they will show up as green for up days and red for down days (periods)
One other point, Stockcharts also has what I think they used to call "oxymoronic candles". Say the close is higher than the open so we would normally have a white box with a thin black boarder, but in a special case this up close is still lower than the previous close then the thin box will be red rather than black. Same thing if the close is lower than the open, solid red box, but if that down close is higher than the previous close the box would then be black.
I know its a bit confusing, and different sites use slightly different formats, but once you get used to it I'm sure you will always use candlestick charts.
News 
Market Data 
Discover 
