There is a bit of a learning curve to them @huynhduc , but take a look at this related post, and also see the links to other posts at the bottom.
It seems though that some of the original documentation I have referenced in the past has either disappeared or moved! 
Pinging @Continental_KNIME_Extension_Developer - do you know where your detailed tutorial/documentation has gone. The link I previously had was this:
It has been referenced elsewhere and appeared like this:
but that now just goes to a generic community/extensions page
Meanwhile, there is a free ebook
and there is a small section at the end that discusses formatting with the Continental nodes.