One of the most important components of any circuit is the methods of connecting power, to device, to it's ground. While there's some basics of covering circuits in this section of our documentation There is one you HAVE to get right, the ribbon cable to the breakout board. If backwards, you could get a bad connection, wrong pin numbers, or worse damage your components. If you're not sure which way the cable goes, there's an easy way to tell. Get an LED, and plug them into the breadboard making a connection between the 3.3v and ground, with the long leg on the 3.3v side, and the short one on ground side.
In this photo, we've used the ground strip which reduces potential pin error. A resistor won't be necessary for this since it will be momentary. Now, pull the SD card from the Pi, and connect the ribbon cable. Once you are ready, plug the Pi in quickly to see if the LED lights up. if it does, your ribbon cable is plugged in correctly. If it does not, you will need to switch the way your ribbon cable is plugged in, and try this test again.
DO NOT LEAVE THE POWER CABLE PLUGGED IN, IT MAY DAMAGE THE LED!