You can store array items in a json file (just rename with *.json instead of *.txt) in the following format:
You can make the data items what ever you want, of course.
You can make the array as big as you like and even turn it into a 3D array by adding extra items within the inner square brackets, just make sure to adjust the size values at the top.
Import the file into the files folder for your project on the "Project" tab.
Add an array object to your game (e.g. yourArrayObject)
Add the AJAX object.
System|On start of layout: AJAX| Request (your json).json (tag "your tag")
AJAX | On "your tag" completed: yourArrayObject|Load from JSON string AJAX.LastData
This will grab your json array and add it to the array object - I don't think you have to stipulate the size of your array object - it should automatically fill up from the json - but it probably doesn't hurt to set the dimensions the same.
Hope that makes sense!