I would boot the Live CD and use Gparted or Partition Editor/ Manager
(the name changes with version). You cna either format the unallocated
space in format that you choose or you can Resize if you do not want
an extra partitions. I am a graphical guy so U would just click on the
partition to make larger in the ribbon at the top and right-click and
Choose Resize and make it larger by using all of the space to the
right or left (it may not allow you to get everything, it usually
wastes a few MBs). Check and double check then hit Apply.

You cannot work on a mounted partition so that is why you use the Live CD.