The ZenPhoto gallery was created by our former webmaster who has given us his credentials but nothing else. What do I have to do as the new webmaster to reactivate this old gallery and make the photos avaialbe to the parent website?

Thanks for any help you may provide!

If you never used Zenphoto before I would suggest to get familiar with it first. Log in and take a look around. If you have a Zenphoto install that is a website for itself.

I cannot answer how to make "photo available to the parent website" depends on how your website is setup. There are third party (unofficial) plugins to use it with Wordpress if you mean something like that.

Maybe post a link to the site in question.

Thanks. I am completely new to web stuff.
On our parent website (www.friendsot.org) we have a 'photos' page that last week was saying (archived) and now says 'not found'. I have admin access to the parent website which is using WordPress.

If you could point me to a basic site that explains how to fix that I would appreciate that!

I can access http://www.friendsot.org/gallery/ fine. Seems to work as intended to me.

If you are completely new to web stuff you should plan about quite some time to become familiar with this. You need to maintain your installations for example. At least the Zenphoto one is quite some versions behind.