What is the best way in python/django to let users add files to the database?
You could simply write static files to disc, and then serve them as static files.  That would be easier, but it depends on your other requirements.
But, from what I understand in your question you'd need:

A form to upload
A upload handler itself which inserts into the db
A view that renders based on a path
Not sure about the urls.py entry.  You'll want something in there to separate this content from the rest of your site, and you'll probably also want something to safeguard against the file extensions that you serve there.  

note:  this has security hole written all over it.  I would be super careful in how you test this.
I am trying to let users create html pages that they can view on my website. So the homepage would just have a place for file upload, then some script on my site would take the file and convert it into the html page and place it at mysite.com/23klj4d(identifying file name). From my understanding, this would mean that the urls.py file gets updated to route that url to display the html page of the file. Is it possible to let users do this? Where would I put that conversion script?