Burnish will only export and view an Org file that has the local file variable burnish-backend defined in it as detailed in (emacs)Specifying File Variables.
When the minor mode burnish-mode is enabled, automated export and viewing of the Org file is done on every file save (save-buffer).
An example of setting burnish-backend is shown below, where the text is appended at the end of the file.
# Local Variables: # burnish-backend: html # End:
Rather than typing the above in an Org file, the command burnish-select-backend will insert this for you, prompting for an export backend with completion support.
To directly export an Org file and view the result, invoke the command burnish by its key binding (default: C-<f5>) or by direct invocation (M-x).
Details on commands and customization of Burnish can be found in the menu sections below.