If you want to stack a shield on top of the FONA Shield, you'll want to pick up some stacking headers and use those instead of the plain header shown here!
Wanna stack? This tutorial shows how to use the plain header to connect to an Arduino. If you want to use stacking headers, don't follow these steps!
Begin by breaking the 36-pin male header into four pieces: one 10-pin, two 8-pin and one 6-pin. Stick the header into the Arduino sockets with the long pins down.
Place the shield on top so that all the little pins stick out through the matching holes in the shield. It should match up perfectly!
Check polarity for the battery!
Snap the uFL connector on, it will click when placed properly
You must insert a SIM card to do anything but the most basic tests. FM radio does work without a SIM but of course you cannot send or receive texts, calls, etc!
The SIM card holder it on the right side of the shield. It holds a very-standard "Mini SIM"
Micro SIMs will not work! Make sure you get a "Mini SIM"