Solder stranded wires to three spots on the NeoPixel ring according to the circuit diagram: power, ground, and data input.

Arrange GEMMA in the center of the ring, holding everything in place with a pair of helping hands.

Cut to length and strip the ends of the wires in order to connect to GND, Vout, and D0~ on GEMMA (referencing the circuit diagram). Tweezers can help get tiny wires in position.

Flip the assembly over and solder the wires to the back of the GEMMA pads. Be careful not to fill in the hold with solder, so that you can still thread a needle through it later.