by Howard Miller.
Change the DocumentRoot setting of your web server (you don't say what web server you are using so it's hard to be specific). For example for Apache...
Before..
DocumentRoot /var/www
After...
DocumentRoot /var/www/moodle
...and restart the server. You really need to know (i.e. find out) a little bit about how the web server you are suing works. It's not a Moodle issue per se.