You'll arm and disarm the system by tapping the lock icon on the home screen. Tapping the gear and then tapping "House Profile" will bring up your system settings, but you won't find very many options.
A Korner system costs $98 for a three-tag setup (converted, about £65). You can add additional tags for $25 each (a little over £15). After the first year, you'll need to start paying a $40 yearly fee to continue using the system (a little over £25). For more on the Korner Home Security system, check out our complete review.