How do you view a websites structure (similar to ftp) without getting the default index page? Basically, how do you browse a websites 'file and folder structure'?
Many websites prevent this and this kind of logic will not work on many sites. Websites developed using a MVC framework has a 'non traditional' way of storing the files.
For example, Ruby on Rails (a MVC framework) has a different folder for the different types of models in the site. You can use the routes.rb file to make it appear that files are located elsewhere in the directories, but it's masked with routing of their actual locations. (not extremely accurate, but gives a dumb-down version of what happens)
Update: To answer your question specifically,
If you're running apache on the website, you can edit your httpd.conf file and add
However, if the website is not yours, then you will be limited as to what you can access. Even if you do manage to find a site structure, through http, would be unable to see any server side executed code.