To reach Nok, you must first complete Green Loontern's quest in The Watchtower to unlock the Moon Base. From here, you can build up several Lantern gates to reach the various planets.
Gold Brick #1
You can meet the Green Loontern at the entrance for a tour of the planet. Follow him around, taking out any baddies that appear. At the end of the tour, you'll receive a Gold Brick.
Gold Brick #2
The Green Loontern has another quest for you: teaching the Indigo Tribe a lesson. Follow him down into the prison and beat up the 20 goons there to finish the quest.
Gold Brick #3
You can also find Ambush Bug here, and he needs help clearing out some other insects. Take out the 25 beetles that show up to earn a Gold Brick from him.
Gold Brick #4
Ambush Bug has another task for you: finding his missing bug pets. Check the area for five beetles running around; when you find one, punch it then lead it back to Ambush. Return all five for a Gold Brick.
Gold Brick #5
You'll find Supergirl down in the prison area. When you talk to her, a bunch of prisoners will escape - 30 to be exact. Take them all out to finish the quest
Gold Brick #6
The remaining Gold Bricks can be found under the beacons in the sky, and one is this flying race above a rock tower. Fly through the rings before time runs out, and you'll receive a Gold Brick.
Gold Brick #7
There's a second flying race above the giant Lantern. Fly through these rings in time too for another brick.
Gold Brick #8
Right by the teleporter is a footrace. Dash through the rings before time expires to win another brick.
Gold Brick #9
In the prison area are several electrical conduits on the walls and underneath a big character cracked tile (others will appear in sense spots). Drain the three charged ones to power up the dead ones, and the nearby chest will open, revealing a brick.
Gold Brick #10
One of the beacons points to this tower, decorated in flags. Shoot all 11 before time runs out to earn a brick.
Gold Brick #11
Another beacon will lead you to this sense spot. Use a sensory character to reveal a target, then shoot it to open the nearby shelter, revealing a brick.
Gold Brick #12
In the large underground area all five gold statues. Melt them all with a laser character to receive on last Gold Brick.