It will be best to get a Free Partition Wizard Disc to extend C: with the unallocated space on the far right. Windows Disk mgmt does not do this easily.
BFK's Tutorial will show you most of the steps you need.
To use Windows Disk Management the unallocated space must be adjacent to C:\. I sugest you to create a partition on unallocated space, move your data to it, delete the 37.17 GB volume and then extend C:\. But if you need to add more than 37.17GB to c:\, go for a Partitioning Software.