Have you reviewed the Measure Writer's Reference Guide? If not that is a good place to start. As far file management with as OpenStudio measures, measure, each measure passes in a model, runs the measure code in the `run' method, on that model, then passes a modified model out. So for basic measures you don't have to worry about ruby file management. Often scripts may load or write to CSV files. For that you need to have some basic understanding of ruby file management.