Hi, where is the template inside FTP?
Can I modify it inside Web Administrator? (I want to add a background image)
Inside http://www.miwebsite.com/index.php/index/admin/settings I only see this
Tema del Sitio
Hoja de estilos del sitio
Layout changing as this one you are aiming requires CSS skills to achive.
You can check further info related to this in OJS Theming Guide, see here:
Public Knowledge Project Team