Not a stupid question at all. There's a thread
here devoted to describing the process. It talks about OmniFocus, but just substitute OmniOutliner wherever you see OmniFocus and you'll be fine.
Once you've followed the directions laid out in the FAQ for getting Applescript set up on your system, you would open the Applescript Editor application, copy and paste the text of Rob's script into a new window in the AE app, and save it with a suitable name in the OmniOutliner scripts directory. Sometimes scripts are posted in such a fashion that you can just download a file and drop it in that directory (the FAQ is targeted at such scripts), but it is more work for the poster to do that and sometimes we don't bother. Once you've saved the script, it should be available for use by invoking it from the Scripts menu in the menu bar (looks a bit like a 3 dimensional script S) while you have OmniOutliner as the foremost application. You can also add it as a toolbar button in OmniOutliner with the View->Customize Toolbar... command.
If you want to change any of the settings, use the Applescript Editor to edit the script and save it again. You can run the script directly inside the editor while tinkering, but be sure to save the final version to the disk if you want the changes to stick.