I would replace them! I promise!!
D'aww, with you being so cute, I can't say no!
Basic is that you're collecting star pieces which can be used to get items from the event. You get them for posting and for performing. To do that, you just click the button under a user's avatar.
FAQ - The link is at the top of the page, just so you know, but way more info is here
Join a team - Goddess that you support for the event, gives you a spiffy icon under your name