Bill has the right advice although it depends upon the version of SketchUp you're using. Assuming you have V2013 or V2014, using the Extension Warehouse directly in Sketchup is the easiest way to go because it'll download and install it automatically. If you are using SU2013 or earlier and you've not installed any plugins before, you may need to set the Plugin folder's permissions to allow you/SketchUp to write to the folder. If you need help with that drop me a PM.
Keep in mind that the cut list will only be as accurate as your Sketchup model is precise. If you need it, I can give you a hand getting everything worked out.