Railworks America

I really need help on this one. Whenever I try to download a file that is labelled RAR. Im never able to view it and not able to install it. I recently downloaded the K5LLA and I tried opening it but I dont have the right program to open it it says. Can anyone reccomend a program to open such files????

Winrar: http://www.rarlab.com/

Thanks sooooooo much!!!

7zip also: http://www.7-zip.org/ ( probably lots of different versions, it's mostly open software ).