I'm not a big expert on this either, but I think you can click Tools in the menu, then Customize in the sub-menu.
When the Customize - Directory Opus window has appeared, right-click an empty area in a toolbar and select New -> New Button. After the new button appears on the toolbar, (with the Customize Directory Opus window still open) double-click the new button, then click Advanced.
In the Command Editor - Directory Opus window, enter something meaningful in the Label field, then copy the code previously shown here into the area at the bottom. Click OK a couple of times to close the customization windows.
Alternatively, instead of creating a toolbar button, you could create a context menu entry as follows:
Settings -> File Types
Select All files, or possibly Recognized images.
Click Edit.
Click the Context Menu tab.
Click New.
From here, it will be obvious how to proceed, I think/hope.