That's a little tricky for the average guy. I suggest taking it to a shop. The reason is that you have transmission fluid in the lines and the only way to replace that is to do a flush. A flush is done with the engine running with new fluid going in one line while the old fluid being expelled from another. If not done right, you could get airlock in the line. I'd have a dealer do it. Cost about $75 and well worth it.