Okay well basically it is what you normally do, except it's a little more competitive. Basically you post a ton and try to get the highest score. With the highest score you can get prizes like shinies, emblems...stuff like that.
To sign up you basically do this:
Post in the thread saying you want to take part. Any time you make a new post, edit that post and make a list of all the posts you make in the section. By each post/topic you make you'll see a number in the top right corner of it. Click that which will take you directly to your post then copy the link of that page and put it in your signup post.
I highly encourage you to read the main post and check out how other people did their lists too. It's not hard at all and there are some really good prizes. :)