@LEARNER: Even using su is not recommended for beginners. You'll tend to forget that you're working from root environment. do as following instead.
Code:
$ echo 'yourusername ALL=(ALL) ALL' >> /etc/sudoers
replace yourusername with your username
and then use
$ sudo command
where command can be any valid gnu command.
eg:
$ sudo yum -y install kino
for kino, you need have freshrpms repo configured. If not done already
Code:
$ sudo rpm -ivh http://ayo.freshrpms.net/fedora/linux/6/i386/RPMS.freshrpms/freshrpms-release-1.1-1.fc.noarch.rpm
then
Code:
$ sudo yum -y install kino