HOW DO I EXTEND PARTITION DRIVE NAMELY C DRIVE
Which version of windows are you using? If it's Windows Vista or 7 for example you can extend it through disk management however if it's Windows XP you will need to use a utility such as gparted for example.
Disk management won't allow you to extend the partition if there is a partition adjacent to it. In this case use a 3rd party partition tool. Any time you mess with partitions, make sure you have a backup first.