Before you delve into the deep end, you need to ensure Apache is set up first. I'm assuming this is a virgin installation, so if you already have Apache things going...be careful what you change. I'm also going to explain setting this up with basic password protection. You can easily let this out, however, if you want to allow access to the repos from everyone.
First thing is make sure you open up /etc/httpd/conf/httpd.conf and at least change the ServerName directive. If you need more help or more complex configurations, then consult the Apache docs please.