Update CentOS and Adding repositories

Update CentOS:

# yum clean all

Get the list of updates:

# yum list updates

Finally, let’s update:

# yum update

Reboot the system:

# reboot
Adding repositories

The standard repositories of CentOS (and Red Hat Enterprise Linux) contain a limited number of packages, including, oddly enough, many popular, and often do not have the newest version. To correct the problem, you can connect additional (unofficial) repository to CentOS-EPEL, RPMForge and Remi.

Typically, repositories are added to the command # rpm-Uvh http://адрес_репозитория.rpm
Either manually adding the file to the directory repo./etc/yum.repos.d/

If you get an error like:
epel-release > = 6 is needed by remi-release-6.5-1.el6. remi noarch.
from the beginning it is necessary to add the Epel repository. Repository EPEL (Extra Packages for Enterprise Linux) is supported by the Fedora project and includes some packages that are not included in the standard set of RHEL (CentOS).
For CentOS/RHEL 6 (64 bit): # rpm-Uvh http://epel.mirror.net.in/epel/6/x86_64/epel-release-6-8.noarch.rpm

Team # yum repolist will show what repositories already connected to your system.

Here are a few repositories that might come in handy:
rpm-Uvh http://download.fedoraproject.org/pub/epel/6/x86_64/epel-release-6-8.noarch.rpm
rpm-Uvh http://pkgs.repoforge.org/rpmforge-release/rpmforge-release-0.5.3-1.el6.rf.x86_64.rpm

Read also:

http://centos.name/?page/additionalresources/repositories

http://howtoit.ru/linux/centos/item/15-podklyuchenie-repozitoriev-centos-6-epel-rpmforge-remi.html