For now, you can do this from the style.css in each section. If you have a link to your site, I can tell you exactly where each line is that you’ll need to edit so you won’t have to search through all of the code. For example, to change the first image of the header and the slider area on the demo you’ll see this on line 1785 –
.head-bg {
background-attachment: fixed;
background-image: url(images/home-img-1.jpg);
background-position: center;
background-repeat: no-repeat;
background-size: cover;
}
Once you upload an image to your site you can add it in the background-image area of the code above. You can upload an image in your Media section of your admin, or you can upload it via FTP depending on whichever one is easiest for you.
This is one of the ways to do it for now, because I will add an easier method by creating a uploader function which will automatically upload your images into place without needing to touch the css code…..similar to the WordPress Header and Background uploader.