All the scraps take place in one of the chat rooms. You just need to show up there when the scrap is going on and scrap and chat. Usually there is some type of inspiration piece (artwork, ad, sketch) or a color palette or some direction given by the DTM that's in charge of the scrap. If it's a speed scrap the goal is to finish a LO in an hour.

I don't do so well with these. LOL sometimes there are goodies for finishing your LO and sometimes it is just fun to get some outside inspiration and meet some new folks.
HTH!