Now there are two Windows 8 plug-in, an excellent one by iUnk and the one built into Scirra Construct2, this might be confusing.
This tutorial is using the Windows 8 Plugin shipped with Construct2 and I am using Beta r104. If you reading this for versions beyond beta r104, the processes may have changed.
Add the Event
Click on the faint "Add Event" and this will automatically add in the Windows 8 Plug-in:
Implement the Condition
There a number of conditions, in this case you want to choose "Is Windows 8 App", if this condition is met then the line of code will run. If it is not on Windows 8 then the app won't run.
Now an action is required, in this case select the "Set live tile text"
Edit Action Expression
In this case you will need to edit the text for the live tile, here is what I used (note that there is a variable "i" in the code:
I used some code where I was practicing the use of Arrays in Scirra, and note that there is only one event with conditions and subevents: