piatkow - 2:21 pm on Dec 25, 2009 (gmt 0)

There are a lot of questions that need answering. In theory its simple:
1. Download site
2. Edit site
3. Upload changes

But you need access to the server on which the site is located. If the creator signed the company up with an external host and walked off with the account details and/or passwords then you have a problem.

If the hosting isn't done in-house then you will definitely need some FTP software to up/down load.

Other issues may arise depending on what the creator did or failed to do.