Take the software that you have purchased for your computer and put the disk in. If you have Microsoft Windows 2000 or XP, it will format your hard drive and create partitions for you. Then it will give u several directions and it will take you through the whole downloading process step-by-step.  After you are down installing the operating system, you can then proceed to other software and download them. The windows setup program looks something like the picture below.

Once this is installed you can install all other software such as drivers, office, games, etc.