This are the simple steps to add a context menu when clicking with the rigth button of the mouse in the selected file.
- Go to edit -> Configure custom actions...
- In the menu click on Add a new custom action.
- Give it a Name that will be shown in the context menu
- A Description
- Write the Command to run (e.g. convert %F %F.png) where %F means the selected files
- Go to the tab Appearance Conditions and choose the type of files that you want this context menu to appear (e.g. in the previous example we should choose Image Files)
- Click OK and Close
I uploaded a video with all these steps in YouTube:
See a more detailed explanation here: http://pclosmag.com/html/issues/201008/page10.html