Redhat 9 reached its end of life a while ago, so there are no more upgrades from Redhat. If you need to upgrade your kernel, you will have to check whether the
fedoralegacy.org project provides any upgrades for Redhat 9 kernels. If not you will have to compile a new kernel from source. Personally I would recommend you switch to a newer Redhat based distro such as Fedora Core or Redhat Enterprise Linux (or free rebuilds such as CentOS).