Datasheet

That's it! Now you can turn off the soldering iron and
plug the IDC cable. Note that one wire of the cable has
a red stripe. That's pin #1. Because the cobbler
connector has that notch, you can only put it in the right
way (whew!)
However, it is possible to put the cable in upside down
on the Raspberry Pi! Check the images on the left to
verify that the stripe is on the edge closest to the SD
card!
Note that the stripe may be red (gray cable) or white
(black cable)
© Adafruit Industries https://learn.adafruit.com/adafruit-pi-cobbler-kit Page 14 of 16