Tie a knot with a sewing needle! Insert the needle under a previous stitch.
Pull the thread almost all the way through, leaving a small loop. Put your needle through this loop and pull the thread through, creating a tight knot.
Don't forget to seal the knot with Fray Check or clear nail polish before trimming the tail closely.
The thread must travel between components to connect them, while avoiding other paths of conductive thread in the circuit. The thread acts like uninsulated wire or traces on a circuit board, but this circuit board is made out of fabric!
The most straightforward connection is a running stitch. You can also learn many more hand embroidery stitches which can have decorative or functional appeal in your project.
As you stitch along, pause periodically to whip-stitch a chainable pixel's ground pad (-).
Turning 180 degrees
Now that all the pixels are anchored by one pad, clean up any stray threads on the back.