This question is open for quite some time now. My hunch is, that this is, because it's difficult to understand what the problem is.
If you want the text "Connector Operations" to appear in the "Cross-Reference" Pod in the "Paragraphs" list on the right side, you will need to add the text to your chapter file "04.1_RESTful_Interfaces.fm". And there it needs to be formatted with the Paragraph Style "H2 Head2" (as you have selected this style in the left list box with the style names). Only then it will appear there.
The Cross-Reference Pod is used to insert new and manage existing cross-references: