Fedora uses
yum command line package manager, see if it's on RHEL too. I could imagine it is. Read
if it is there, to see what it's about. Basically you update the package list with
and install stuff with
for example. Yum deals with dependencies if possible, i.e. if they are found from the reposities; this should work as long as you use the official reposities, but if you enable non-official reposities they may have some versions which conflict.