What do you do when you know nothing about a subject? I ask Google.
Google has been my friend for many years and helped me a lot on my everyday life. Of course you must know how to deal with it, there is so much garbage information on the web and you must sift the wheat from the chaff (BTW, how this expression was written in English I leaned now: Google has been my dictionary too).
Looking for info about the ruffler foot I found a lot of interesting things. The last one was picked up from a comment on Amazon.com and it's a very complete material on how to use the ruffler - and it's free! Here is the link, you just have to sign in to download this document:
When I first tested this foot I thought it would never work. It's a little more complicated then the other feet, but not a monster as it seems. I won't talk much about this foot as the pdf above can tell you pretty much everything about it.
I haven't done anything with it yet besides testing it with a few fabric scraps and have no plans so far, but it seems to be a nice tool for you machine. I didn't even wanted to buy it in first place, but it came with the Distinctive set and it turned out that it was a good foot to have.
It ruffles your fabric in different depths and you can also attach a ruffler to a plain fabric. There are also helpful videos on Youtube (another teacher of mine), just search for "ruffler foot". This one shows how to attach the ruffler to another piece of fabric: