The easiest way to install software in RedHat is to use
apt-get. Download the two binary packages, open up a terminal, and as root do:
# rpm -ivh apt*
then sync up apt:
# apt-get update
install synaptic:
# apt-get install synaptic
Now synaptic is a nice little gui for apt-get. Fire it up:
# synaptic
and you can browse the packages you want to install. If you want to install rpm's manually just do:
# rpm -ivh <package>
I suspect you were double clicking on the rpm packages in some sort of file browswer.
P.S. Its probably a good idea to update all your packages as well:
# apt-get upgrade