Hi,
Your theme Floristica uses a background image for the header picture. The name of the image is “body-back.jpg”, it’s 780px wide, 235px high, and 66.9kb.
The background image is assigned in your style.css as follows:
#root{
width:780px;
margin:0 auto;
border-top:0;
border-bottom:0;
background:url(images/body-back.jpg) 0 32px no-repeat;
}
The path for the image (where it’s kept in your WordPress directory) is “images/body-back.jpg”. This is most likely your theme’s images folder.
The easiest way to do this is:
1) Create a new image to your liking of the same size as the original (height, width, and overall file size), and name it the same, “body-back.jpg”.
2) Save the original somewhere in case you want it back later.
3) Replace the original image with your new image in the images folder. You don’t have to mess with anything in style.css, as long as your new image has the same name and size as the original image.
The new image should appear in the same manner as the original!
Good luck!