Installing and upgrading help

IIS or Apache (or something else)?

I assume you mean you want to use Moodle and also run a web site on the same machine?

You have two basic choices.

1. Read about virtual hosts (for your web server software)
i.e. mymoodlesite.mydomain.com and mywebsite.mydomain.com

2. Read about virtual directories or aliases (for your web server software)
i.e. www.mydomain.com/mymoodlesite and www.mydomain.com/mywebsite

It's not really anything to do with Moodle - you need to do some reading about setting up your web server.