I built this bike for my wife a few years ago, it's stable and the kids love it. This summer during the heat wave we were riding later than normal just to stay cool. We needed lights on our bikes and I thought this would be great if it worked. At the time of the build I did not take pictures but I will try to explain how I did it. I'm terrible with electrical stuff and had to get something simple. I found some micro LED thin string wire online that came as a kit with battery pack included, the price was reasonable it was worth a shot. I was not sure how to mount it to the parasol, I thought about tying it with many little fishing line loops (terrible) then I remembered my hot glue gun. I unbent the wire LED and clamped it into place on the umbrella then added a little glue, waited, moved clamps, ect. It was holding but I was about 8 inches short on the radius. I ordered another kit snipped off about ten inches and glued it on. The wire is very thin and when I touched the added length to the old I got nothing. I figured there was some circuit that could only support the original amount of LEDs.
A couple of days later I went back to it and tried sanding the wire to get better contact. To my surprise inside that thin wire is really thin copper wire. It was working so I soldered the wires together and ran the cord down the handle and inside of the box. I used hook and loop to mount the battery box under the seat so that I could easily remove it for battery replacement.
If I was going to do it again I would have gone with a soft white LED
The end result is great for cars being able to see us, the kids have light, and I'm happy with it. I realize this is pretty basic but for a guy who is terrible with anything electrical it was quite satisfying.