making environments

Does anyone know how to make a custom environment? Is there a program that you need???[confused]

I use NL construction kit's environmental editor to add some light effects and fog to already existing environments, but it won't create new sky boxes. I know that supposedly you can use Terragen to do that. I have not figuered terragen out, or how to export the sky boxes, once they are created but would like to.

ok that sounds kinda hard but thanks for the help [:)]

so does the environmental editor comes with NL? because i cant find it [:(]

no, look for it in the toolbox at nolimitsdevcenter.net

ok thanks!