Thanks & Regards,
go to "edit VM settings" in workstation. Select the disk and expand it to the desired size.
After that you need to expand the NTFS on that disk as well.
If you only got the C: partition on that disk and the D: on a seperate VMDK, you can simply go to volume management inside windows and expand the C: partition.
If not you can boot a live linux like knoppix inside the VM and use gparted to move and extend the C: partition.