If you mean installing WinXP/Vista or any other OS (Operator System)...
You buy the boxed install CD.
Now you have 2 options depending on your PC:
- During POST (see URL) you see a Boot Menu option that allows you to select where to boot
- You open your BIOS Setup and change the boot-order to CD-ROM (aka CD drive) 1st, HD 2nd
Whichever, you want to boot to the OS setup CD.
WARNING: If you are installing WinXP, there MAY be a problem if your PC uses SATA hard drives
. WinXP CD does NOT come with SATA drivers. So when you boot to the CD, at the first dialog where it is copying files, there is an option on the Statusbar you use to load additional drivers. For SATA drives you MUST use this. Problem, you have to have some other media (floppy, USB Flash drive) with the drivers for your motherboard. IF your system uses SATA drives, contact the motherboard's or PC manufacturer support and see if they have a solution, to load SATA drivers during WinXP install so it can see your C:
On my DELL at work [Del] = Setup (BIOS Setup), [F2] = Boot Menu
NOW, just follow the on-screen instructions. PAY ATTENTION to messages on the bottom Statusbar of windows
. These messages tell you what to do next. Also, ALWAYS do a Full NTFS format.