-bash: yum: command not found

-bash: yum: command not found

I have one server with Red Hat Enterprise Linux AS release 4 (Nahant Update 3) installed on it. And i tried to add the online repo on it.
using this link
enter link description here
And everything goes smooth. But when i tried to install any package
it replies
-bash: yum: command not found
There are some repos in /etc/yum.repo.d/
mirrors-rpmforge mirrors-rpmforge-extras mirrors-rpmforge-testing rpmforge.repo
The content of rpmforge.repo is
[root@Backup yum.repos.d]# cat rpmforge.repo
### Name: RPMforge RPM Repository for RHEL 4 - dag
### URL: http://rpmforge.net/
[rpmforge]
name = RHEL $releasever - RPMforge.net - dag
baseurl = http://apt.sw.be/redhat/el4/en/$basearch/rpmforge
mirrorlist = http://apt.sw.be/redhat/el4/en/mirrors-rpmforge
#mirrorlist = file:///etc/yum.repos.d/mirrors-rpmforge
enabled = 1
protect = 0
gpgkey = file:///etc/pki/rpm-gpg/RPM-GPG-KEY-rpmforge-dag
gpgcheck = 1

[rpmforge-extras]
name = RHEL $releasever - RPMforge.net - extras
baseurl = http://apt.sw.be/redhat/el4/en/$basearch/extras
mirrorlist = http://apt.sw.be/redhat/el4/en/mirrors-rpmforge-extras
#mirrorlist = file:///etc/yum.repos.d/mirrors-rpmforge-extras
enabled = 0
protect = 0
gpgkey = file:///etc/pki/rpm-gpg/RPM-GPG-KEY-rpmforge-dag
gpgcheck = 1

[rpmforge-testing]
name = RHEL $releasever - RPMforge.net - testing
baseurl = http://apt.sw.be/redhat/el4/en/$basearch/testing
mirrorlist = http://apt.sw.be/redhat/el4/en/mirrors-rpmforge-testing
#mirrorlist = file:///etc/yum.repos.d/mirrors-rpmforge-testing
enabled = 0
protect = 0
gpgkey = file:///etc/pki/rpm-gpg/RPM-GPG-KEY-rpmforge-dag
gpgcheck = 1