The NeoPixel strand's data in pin is connected to pin 13 on the Feather.

Connect BAT and +5v to the + side of the screw terminal. Connect G on the Feather and on the LED strand to - on the screw terminal.

The LED seed pixels we're using can be tricky to wire up. They aren't generally marked, though if you look closely you can sometimes see a copper wire spooled around the +5v wire. Data is usually (but not always) in the middle, and it's difficult to tell which is the IN end and which is OUT. So, don't assume this diagram is correct for your pixel strand. We'll go through testing on the Assembly page.