The display board information can be found in this post :
http://www.raspberrypi.org/forum/viewto ... 45&t=64993
The specific information you are after is mention in this paragraph :
"Screen and TP use hardware SPI ( SLCK, MOSI, MISO, CE0 & CE1 ) plus 3 additional GPIO lines ( GPIO17, GPIO18 & GPIO25 ), keeping the other GPIO lines free for other uses - the pcb has a 'breakout' GPIO port to connect too."
Search the forum or google for the gpio pinout diagram of the Pi.
To access the unused gpio pins the display board has a gpio port pass- through connector so that you can attach additional hardware using those unused pins. You'll find some more pictures on my eBay listing :
http://cgi.ebay.co.uk/ws/eBayISAPI.dll? ... 1447185030
Hope this helps
Various male/female 40- and 26-way GPIO header for sale here ( IDEAL FOR YOUR PiZero ):