The top of this help page explains how to customize your E-junkie button code to replace the standard button image with a custom image:
The custom image URL you'd use would depend on which folder/subfolder(s) of your site you stored it in -- e.g., if you put it in a folder named
images in the root-level folder containing your site, the URL would be like
Tip: a "root-relative" URL like that (starting with a
/) means the domain part of the URL (
http://www...etc.) is presumed to be the same as the page itself, which can be handy if you have multiple domains pointing to the same site, or if your site can load with either
https, or if the URL might go into pages nested in different subfolders of your site. To test URLs, you can try typing/pasting them into your browser's address bar; when the image appears, you'll know you got the right URL for it.
This page has some tips for finding the file URL of remotely-hosted downloads, which you may also find helpful to find the URL of your custom image: