Just insert them in a section of the script where you'd like to check if the code is being executed. The calling convention is fairly simple, especially if you just want to print a static string:
PrintToConsole "Line X is running"; OrDebugPrint "Line X is running"
If you use http://fose.silverlock.org/fose_command_doc.html#DebugPrint, you'll also need to use http://fose.silverlock.org/fose_command_doc.html#SetDebugMode in order for the messages to be printed to the console.
The advantage of http://fose.silverlock.org/fose_command_doc.html#DebugPrint is that you can leave these lines in your script for later debugging without having to worry about a performance hit or console spam - they will be disabled by default but can be enabled via http://fose.silverlock.org/fose_command_doc.html#SetDebugMode, whereas you'd have to comment out or remove http://fose.silverlock.org/fose_command_doc.html#PrintToConsole lines if you want to avoid console spam when you release.
You can also print information from variables, like this:
DebugPrint "The condition of the player's weapon, %n, is %f" PlayerEquippedACR ACRcondition
See http://fose.silverlock.org/fose_command_doc.html#FormatSpecifiers for more info on this
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