Well, simple, two things, firstly, open the config.php file in the Moodle root folder. in the line
$CFG->
wwwroot = 'http://localhost';
Change it to read:
$CFG->wwwroot = '
http://you.ip.address.here/moodle';
if you have Moodle in a folder of its own. If you are not sure, open your
IIS.ini file and look to see what the document root folder is, (something like wwwdocumentroot or some such from memory). If you are using
Apache, open the httpd.conf file and look for "documentroot" that will tell you.
Second, you might want to look at
Moodle Docs, the
Beginning Administration pages, there is a lot of help there for common issues for new Admins. The more information you have, the more quickly it becomes available to you, allows you a considerably less level of frustration when you first get started. There are alos links off to other docs that provide a lot more help.
Good luck...