Without knowing details of your system, it's impossible to offer much useful advice.
If your site is running Django, you will typically be able to log in to the admin at /admin (i.e. append "/admin" to the address of the site in your browser).
But, you will need a username and password to proceed any further than that.
If your site runs a well-known Django application, then you may be able to get some help about using it.
However, you need with some urgency to get hold of as much information as possible from the previous site manager, and to find out who set up the site in the first place.
Daniele