The CentOS directions are pretty good – follow them to the letter. The directions in the installed /etc/httpd/conf.d/subversion.conf – less so. In particular, your <Location> node should look something like this, in order to work (ignore the rest):
<Location /repos> DAV svn # path to your repo here SVNPath /var/www/svn/repos AuthType Basic AuthName "Subversion repos" AuthUserFile /etc/svn-auth-conf Require valid-user </Location>