Welcome to LQ.
The manual (man yum) http://linux.die.net/man/8/yum
Yum is useful. Use 1) su 2) then other commands :
yum search <name> ( or part of name.)
yum provides */<file>
yum install <package-name>
yum list all > all-packages.txt : Will save a list in /home/<name>/.
( And /tmp/ is not supposed to be accessed, permissions may change.)