Many Thanks folks!

Here's all info I have been given to work with. Should have posted it earlier, sorry. It was buried in a heavy load of emails.
"First he will need an ftp software to access the files on the web site server. The passwords he needs are included in the email from the website. The files are simply opened by internet explorer and edited in a simple text editor. I used Wordpad or Notepad that came with windows, nothing fancy"
"The site is written in HTML with a little PHP throw in here and there
as we needed it to get more complicated things to work, so it is
actually a pretty straightforward site. Your guy will need software
to upload and download files to/from an FTP server. I also saved many
of the older files there too, just in case we ever needed to
reactivate any of them"