Website admin fired, me taking over but really confused.

Hello all! Sorry if this question is long but I’m in real need of some knowledge, going to try to summarize. OK so I got a call from a friend who is manager in a company and told me that they had a huge fight with their website admin/designer and fired him, he made a last troll (left some text in white with white background so you can’t see it and removed some images) and left. They don’t know anything about websites or anything at all! This company is like 80 years old and it’s like technology never happened and they’re still in the year 1920. So I had to recover all the passwords and info I could, they guy wont answer the phone ofc so he is like nonexistent and I managed to get the following:

1. Our host is DigitalOcean with a virtual machine running: Ubuntu Joomla! 3.6.2 on 14.04 it’s like the basic service. The domain is with another company but I think that’s irrelevant.

2. I managed to get the SFTP running and could browse the files in the VM, I can see bin folder, boot, ETC folder with apache2 inside it and many others, I can see var/www (a bunch of folders) /html and I see index.html and index.php and many other files and folders.

3. I was able to connect the tool that I use to edit websites (Dreamweaver) to the SFTP and try to see what’s going on but…

When I open index.html I see only a text that says: It Works! and I can’t edit the thing! btw the website is this: http://www.alfonsosenior.com/ … I really need to edit this file (well that’s what I think) so I can put back the images deleted and the text that’s not showing because of the color!

And last, I’m no web developer or designer, I’m a windows server active directory administrator for another company but these guys really need help.

Thank you and sorry for long post!