How can I edit, add, or created new features and forms in this field? (see attached)
From the Menu Bar, go to Manage -> Administration -> User interfaces
While you did not ask this question, if you wanted to create a brand new interface you would do it from this screen.
However, you'll want to look for the Standard Objects Editor ( standard_object_ui) and click on the Edit button. On this page, you will find a section for what Screens are displayed and you can Add Screen. Then clicking the edit button for a particular Screen, you will get two columns of metadata elements: Available editor elements as well as Elements to display on this screen. Simply drag the available metadata elements from one column to another to add or remove items from the Screen. Then if you want to further customize the metadata element, you will want to hit the "i" icon which will pull up a context menu for that specific bit of information. An example of why you might want to use this context menu is that if you wanted to create a metadata list for the method of creating a photographic print, (e.g. silver gelatin, daguerreotype), you can limit the the element to the type Images or if you created a subtype, Photographic Prints.
Many thanks sjenson!! you helped me a lot!