Check out their Facebook page and Official Website!
SMROOKIES is a part of SM's new "Co-Creation" system. Fans will be able to participate in preliminary events and showcases before their official debut. The rookies will have the freedom to form different groups with each other, and show their day-to-day lives and practices to their fans. These rookies will also participate in concert and variety shows to win the hearts of fans. We can also expect covers of songs by their company's seniors and their own originally composed songs in open performances to showcase their talents. (Soompi)
One by one the Rookies were released through Facebook. A few music clips, dance clips, and casual clips were also released on SM's YouTube Channel. Also, on April 13, a website, www.smrookies.com opened with the words "Coming Soon," along with a clip of the rookies hanging out and having fun without showing any faces.
Judging from the above YouTube clip, I'm assuming SM will be showcasing their "Co-Creation" system through a TV show (like WINNER or even EXO Showtime) or webisodes on smrookies.com.