Replace Home page background images

Hi Jerry – you can replace the front-page panel images with your own by going to Customize – Theme Options, and then choosing one of the panels. For example, the panel over which your tagline appears is the “Title” panel.

More info on setting up Harmonic:

https://wordpress.com/themes/harmonic/
https://harmonicdemo.wordpress.com/front-page-setup/

These forums are for folks running the WordPress software on their own hosting, not on WordPress.com. If you need further help with your theme on WordPress.com, feel free to post in the themes forum here:
https://en.forums.wordpress.com/forum/themes

Here are some tips on getting help in the WordPress.com forums: http://en.support.wordpress.com/getting-help-in-the-forums/

You can also access the live chat support option when available here:

https://wordpress.com/help/contact