Hi Meesh and welcome.
Not asking many questions, are you! :-)
All you need is a PC, although some people have sucessfully used a Mac. You need a good view of the sky from somewhere near your computer, so that the aerial supplied with the box can also have a good view, because it's line-of-sight - it can see the same way as we humans can see.
If you can't arrange it like that, you need an external aerial to fix on the roof to get a better view (about 50 GB pounds), and low-loss cable to connect it to the RadarBox. I've got 15m of cable that cost me 100 GB pounds, including the adaptor to connect it. Some people use a mast-head pre-amplifier to boost the signal, but I'm happy without one.
After that, you just need to download the full version of the latest software from this site
http://www.airnavsystems.com/RadarBox/support.html (you can download it in advance and run it in demo mode for free - strongly recommended), and then it is literally plug-and-play. You don't need the CD at all, except that it carries the ID and password to get the box running.
If you connect to the internet as well, you get extra goodies - the aircraft database that comes with RB gets constantly updated, you get photos of the actual aircraft you're picking up, and details of many of the routes they're flying, and you can share your info on the network, which other users can see, and you can see the info that they're picking up (with a 5 minute delay).
Any more questions, just ask!
Rod