for RHEL6 use "yum" that is what it is there for
Code:
su -
yum install ndiswrapper
now seeing AS this IS the NOT free RHEL6
you HAD to have BOUGHT the required license
https://www.redhat.com/apps/store/desktop/
the Standard 1 year IS recommended
also WITH the required license you get access to the red hat knowledge base
search it for "ndiswrapper"
https://access.redhat.com/knowledge/search
you will have to login to the red hat site to use it