As Crossroads has indicated, when you install a program to a PC, it's not simply a matter of adding some files to the PC's hard drive. (If it was, you'd be able to copy them easily to any other PC). Most software also makes changes to the PC's registry. If you simply copy the program files to another PC, the program won't run because it won't be able to locate the relevant registry entries.
Attempting to copy registry entries is
(a) very complicated ; and
(b) courting disaster. (One small error could render your PC unusable).
Anyway, why on earth are you trying to copy Winrar? IZArc is at least as good, if not better. It's free and available here:
http://www.izarc.org/
Chris