In a button, menu item or hotkey.
See the toolbar editing tutorial video for a quick-start on how to edit buttons.
Edit: Including follow-up info from our private message in case it helps anyone else:
You create a new button on your toolbar which runs the command I provided, then select the files and click the button you created.
To create a new button, select Settings -> Customize (a Customize window will appear; ignore that for now), then right-click some empty space on your toolbar and select New -> New Button.
Paste the command I provided into the Function: field of the button, then click OK in that, and click OK in the Customize window that appeared earlier.
Now select a test file and click the button. Its description should be changed to its path.