Reading the guide from this site

chapter 2 introduction: says,

"So, in order to begin your installation, you have to copy the contents of the full html directory to the root directory of your environment. What was that again?"

Then, a few paragraphs below that it says:

Now, if you're installing your site in a hosted remote server, you'll have to upload the html directory to one of the directories you have access to. In this case, you'll probably have a public_html folder, and that's where you'll need to upload the complete html directory. Again, after uploading everything (probably with an FTP client software), change the name of this folder to xoops. Since you'll be installing in your root folder, in this case you'll access your site typing in your browser http://www.yoursite.com.

So which is it? Do you copy the "contents of html, or the whole folder?

If you upload the content of the html folder into your root folder, you'll have access to your XOOPS site at http://www.yoursite.com/

If you upload the (whole) html folder into your root folder, you'll have access to your XOOPS site at http://www.yoursite.com/html/

It's your choice, no rule given

Personally, I would recommend copying the contents of the /html directory into a /xoops directory, to avoid mixing up the XOOPS files with other files in the web root directory.

You can add a redirection script in the web root so that visitors don't have to type in the "/xoops":