I am facing a problem of using yum , it cannot fins any repository

yum info
Was not possible to find any OpenClient repositories.
Could not retrieve mirrorlist http://mirrors.rpmfusion.org/mirrorl...on&arch=x86_64 error was
14: PYCURL ERROR 22 - "The requested URL returned error: 404 Not Found"
Error: Cannot retrieve repository metadata (repomd.xml) for repository: rpmfusion-free. Please verify its path and try again

I put folowing entry in /etc/hosts but could not find any repo

80.239.156.215 mirrors.fedoraproject.org
213.129.242.84 mirrors.rpmfusion.org

any one have any idea

Indeed there is no fedora6Workstation repository. Maybe did you mean EPEL6 or Rpmforge for CentOS6? What OS do you have?

It is RHEL6

If you're using RHEL6, you should stick strictly to the (paid for) RH repos.
Post your repo file contents.
If you use anything else, RH will refuse to support.

If you don't want to pay, switch to Centos 6 (free rebuild of RHEL; inc updates but not support).
Still not a good idea to add extra repos to the ones that come with it unless you know exactly what you are doing and use http://wiki.centos.org/PackageManagement/Yum/Priorities