Change Home Page Image on Pilot Fish Theme

I have been struggling to change the front page image of my soon-to-be web site, which uses the pilot fish theme. I have tried two approaches based on what I found searching through previous discussions:

First:
Using the Editor I went to the Pilot Fish Style Sheet. Under
Featured Content, I changed the background-image url (“home_banner.jpg”) with the url of an image I have stored in my media library. This is what it looks like:

/* Featured Content */
#featured {
background-attachment: fixed;
background-image: url(https://yoga.jilldpatton.com/wp-content/uploads/2013/02/JK-view-up-tree.jpg)
background-repeat: no-repeat;
background-position: center top;
height: 380px;
display: block;
text-align: center;

The first several times I tried this, nothing happened. Eventually the Bavarian Forest image disappeared altogether, but my image never showed up. I have no idea what I did!

Second:

I began to try the suggested approach where I would rename my desired background picture “home_banner.jpg” and upload my image to:

yoursitename.com/wordpress/wp-content/themes/pilot-fish/images/

I tried to get to this site by literally using “yoursitename.com” which redirects to a web hosting service, and to use “yoga.jilldpatton.com/wordpress.wp-content/themes/pilot-fish/images”, which gives me a 404 dead-end error message.

I didn’t get any further than that (I haven’t renamed my file or figured out how to ftp it …)

Help! Can you tell me what I’m doing wrong?

Thank you!