When you visit a website, such as http://www.example.com/upload/test.html, the web server is going to take everything after the domain (i.e. /upload/test.html), append that to what is usually called the Document Root (e.g. /var/www), and come up with a path of /var/www/upload/index.html.

In your case, it looks like your document root is also /var/www. So, if you are uploading images into /var/www/upload/, then you want to point the browser to http://yourdomain.com/upload/$filename. You also have the option of dropping the domain and simply providing /upload/$filename.