How do you help a design get printed

I'm new, I've been part of Threadless for two years but just because I signed in to help a friend with his score, but I've been seriously into the page for like two months. So this question might be silly, but since I'm new, there's some things I'm still trying to figure out. So... I saw on my profile that I apparently helped a design get printed, I haven't ordered or ask to print any t-shirt yet, so my question is how this happened? because there's a lot of cool designs here and I'd love to help some more get printed then.