what have you done so far on the older RHEL5 ( 5 point WHAT 0,1,2,3,4,5,6,7,8 )
also have you gone through the red hat documentation ?
and looked through the red hat knowledge base
the docs for the older 5 series is in the middle of the page
the "knowledge base "
log in to red hat with the user/pass you set up with the license