Dear Auge,

Thanks to your kind help, I am starting to see the light. I am starting to understand how to do multi-site.

But I still do not understand this point below:

No, do not copy the installation. Install a second forum independent from the first one in the other directory (in directory 2nd-forum) with different table and cookie prefixes.

After installing the 1st forum, I can no longer access the /install folder through my web browser. So, how can I "Install a second forum" as you said? How can I run the install again?

Thank you so much once again.