Step 6: Solder and Clip Rows 2-4 and Then Add the Bridge
Rows 2-4 are the same as row one, EXCEPT that that in rows 3 & 4 you are going to leave the 2nd column unclipped rather than the 1st column.
Again, keep that row clipping map in front of you because if you (like me) stop paying attention for a minute you'll end up clipping off the wrong lead and then banging your head down onto that tiny bed of nails pointing up at you, causing a bizarre grid of puncture wounds on your forehead that will inspire a series of less-than-flattering nicknames that will linger long after the scab-array has been picked off. Really. I know.
When you finish with Row 4, you are going to slide on the bridge as shown. The holes in the bridge should be on side of the matrix board you have been soldering.
I've missed this step a few times and then realized it only after I finished soldering row #5. It is possible to cut the bridge and get it on, but it is much easier to not miss this step in the first place.