First step is to install dependencies
$ sudo yum groupinstall “Development Tools”
$ sudo yum install kernel-devel
Mount the Virtualbox Additions CD ISO. You should download the virtualbox additions iso from http://download.virtualbox.org/virtualbox/ depending on your version of Virtual Box.
$ sudo mkdir /media/cdrom/
$ sudo mount /dev/cdrom /media/cdrom/
$ cd /media/cdrom
$ sudo ./VBoxLinuxAdditions.run
Before this step, create a shared folder in your host system. Say for example, if you created a shared folder named “CentosShare” in the host system you will follow the steps given below to access the share from within Centos.
$ mkdir ~/share
$ mount -t vboxs CentosShare ~/share