I have just installed a new main hard-drive (c drive) how do i get my computer to recognize it
beat it with a hammer! no that not it ,you make sure its hooked up correctly and turn on the computer ,you need to tell us more also ,Is it a SATA harddrive ,did you boot to a windows cd and try formatting and loading windows to it ! id its SATA and you have winxp ,you will need a flopy drive in the computer to install sata drivers for it to see it ,if no floppy drive, then you will need to slipstream the sata drivers into a new windows disk with a program like Nlite http://www.nliteos.com/
and if all that is over your head !then you will need to take it to a computer repair shop or your neighborhood know it all .
agre with all above but also check if the BIOS recognises the drive at startup. If not you may have to enter via driver as above or enter in bios by hand the drive details or configuration of cables masters and slaves...