Solder the RGB LEDs.
You might want to attach the mounting screws on four of the foles on the PCB. This will give the PCB some “lift”, so the the LED leads can stick out of the back of the PCB while you insert them.
Cut the leads only long enough to solder, then insert into the PCB holes. Start from the inner-most circle, one circle at a time. I recommend soldering only one lead per LED first, check the seating/positioning of the LEDs before soldering the rest of leads.
Once all leads soldered it’s very hard to adjust the positions.

Published April 9, 2012 at 687 × 687 in Aurora 9×18 mk2 Assembly Guide