The Spark Core team has great documentation on how to set up your Spark Core device to your wireless network. Throw in that USB cable that came with it and get the device up and running.
Hook up one end to 3.3V and the other to digital pin 1 on your Spark Core. The reed sensor works as a switch, one module contains the electrical components that separate and come together based on the other module which is a magnet. When the magnet is next to the electrical module, the switch gets flipped.
NeoPixels are very easy to wire; connect the VCC to 3.3V, GND to ground, and DIN to digital pin 2 on the Spark Core. As an optional step, cut out a square from a normal piece of paper and tape it over the front of the NeoPixel to help diffuse the light. If you’re spendy, try using black vellum for a really solid black overlay.
Make the connections listed above and boot up the Spark Core. It'll require downloading their mobile app and pushing your sketches to the device through the web browser.