The code I posted can be pasted into a editor (notepad ect.) and either "save as" sigma4.nec or just save as a .txt and change the name to .nec instead of .txt save it in the 4nec2/models directory.
Start the 4nec2 program, go to the little folder below "file " this should bring up a browse for file window ,find/select the sigma4.nec file click open.
If you want to see and follow the code ( it's hard in notepad ) go to settings and select "nec editor " then "edit input" or F-6 then the code will become more clear I'm sure
If you click on a GW line (geometry wire) it should highlight the wire in the "geometry window"
The NEC editor (new) is even more "friendly" and more more powerful
The geometry editor I almost never use but others love it ( it wont allow variables) but can be useful in early stages of model building .
The same little folder icon under file cen open your .ez models just go to the bottom drop down and select all files or .ez before it will let you "see" .ez or other formats.Also allows conversion to .nec format.(edit ..OPPS I see Henry
HPSDalready said that.)
F-1 brings up and almost overly helpful help menu.
Hope that get's you started.