please use more useful thread titles, and please search this forum for your question before asking questions.
I'll still answer anyway tho.. cos i'm nice.
Easiest and most common thing for a newbie to install is an RPM (Redhat Package Maintenance) file, which come with Redhat, mandrake and other popular distros.
Assuming you've got gnome already installed on yuor system, then run the 'gnorpm' program from a console, and that'll give you a nice GUI to add and remove packages. if you've not got it installed, then you'll need to use the command line:
from console run
rpm -iv /location/of/file/file.rpm
which will install the file, assuming there are no dependencies.
if you do get depency failures, then (esp if you're installing from the RH71 cd's) you should have the required files on disk. look through the disk contents to find the right one, or if you get asked for something nasty like 'afile.so.1' or something, always look at rpmfind.net, and search for the file name, redhat files come up in green, and you should already have those files on your cd's.
worry about tar.gx files later... or wait for someone else to fill in that bit.