Use the > and ^ controls to expand or collapse the content.
Use the ... control to expand attributes of a node.
Use the Edit Raw... control to edit the contents of a JMX Element in its raw xml form. This usually is the UI for JMX elements that have not yet been mapped to a UI view.
Use the regular HTML controls - texboxes, checkboxes etc to edit the values of JMX fields. Tab out after editing.
Click the Save button to upload back the modified file. This will not work on the Github-hosted demo for obvious reasons, but can be turned on in your environment by setting "demo": false` in lib/config.json or changing it in the call to init()