Hi Kara,
Thanks for reaching out with your BoldGrid Post and Page Builder questions.
In order to change the image and opacity of the hero image here you’ll need to select the overall section containing it. Any section can contain many rows, columns and elements nested within it so you want to be sure you’re selecting the “black “section tab” when you hover over your hero section.
From there chose “Change Background” and the controls settings for that sections background will appear. Click Image to change your image and Settings to open the control tab to change the sections opacity.
I hope this helps Kara! Please let us know if you have any other questions for us.