4NEC2 has a *huge* learning curve, for lots of reasons.
The first and biggest one is that the code was written long ago in FORTRAN. Data files were designed for punch cards (I'm not kidding) with a very unfriendly interface which has zero tolerance for errors. Data output is... a bunch of numbers. Great for hardcore engineers, I guess, but it doesn't mean much to me.http://www.qsl.net/wb6tpu/swindex.html
is an excellent archive of NEC-related code. You should find some GUI frontends that may work for you, and someone's even ported the code to C which makes it easier to build.