"Can you explain jsut a little how I would achieve this in post?"

It can be a little complex if you've never done it before, and without getting into an entire tutorial on how it's done in this thread, the basic gist would be to mask off a particular area of your background, and use layers to composite it over the figure. There's other meathods to achieving this as well, some better than others. My advice would be, if it can be done in your software, to do a search on Google for masking and compositing for that software.

"Which programs should I use? or should I say which one do you guys use?"

I wouldn't wanna tell you what you should be using, because it's a matter of preference to the individual. However, I would recommend something like Adobe AfterEffects or Discreet Combustion to do intermediate to advanced video compositing like you want.

Personally, I use Combustion 3.

---

Tools :  3dsmax 2015, Daz Studio 4.6, PoserPro 2012, Blender v2.74

System: Pentium QuadCore i7, under Win 8, GeForce GTX 780 / 2GB GPU.