For anyone to assist you with a meaningful answer I recommend you spend more time and effort with your question content and outline more requirements.
At this stage I do not understand if you are trying to increase a physical PC or a Virtual Machine, if you are asking how to increase the capacity of a virtual machines "disk" then I need to understand:
1. The version of vSphere.
2. Hardware version of your VM.
3. Do you have a vCenter server or do you connect directly to hosts to manage your VM.
Lastly, Given this is a Visualization Forum, typically assistance for Windows 7 operating System would not be found here; I recommend you head over to Microsoft's site for support with Windows 7.
You can expand the size of the VMDK disk while the virtual machine is online. However, you must reboot the guest operating system (OS) in the virtual machine so that it is aware of the size change of the VMDK disk.
Also, ensure that the virtual machine is not running on snapshots, as this prevents the VMDK from being extended.
Depending on the guest OS in the virtual machine, there are several methods available to increase the file system within the virtual machine.
If the partition you are extending in the virtual machine contains the Windows Operating System, you may need to use a 3rd party tool to extend the partition.
If you have another Windows virtual machine with the same version of the operating system, you could temporarily attach the operating system VMDK to this virtual machine (known as a helper VM) and extend the file system on the VMDK from this virtual machine using the Windows DiskPart tool.
If the VMDK disk you need to extend does not contain the operating system disk then you can use DiskPart in the original virtual machine without the need for a helper VM.
For more/related information on extending a VMDK disk using DiskPart,
Note: Windows Server 2008, Windows Server 2008 R2, Windows Vista, Windows 7, Windows 8 and Windows Server 2012 can expand the volumes from the Disk Management in Computer Management. Right-click on volume and click Extend Volume.
Instead of rebooting, you can also try re-scanning the disks in disk management. It should see the additional space after that, then it'll just be a matter of running diskpart to extend.