What is a workgroup?
A workgroup (in this case) is a group of computers, both workstations and/or servers, that is identified by a single common name.
Why does it matter what my workgroup is?
For general and simple home networking, every computer should probably be in the same workgroup to simplify tasks such as file sharing.
How can I change my workgroup?
First, many notebooks that are for work have a specific workgroup and it should not be changed. The easiest and most simple way is simply to change the workgroup of all the other computers to match, but make sure that you don't change any other network settings on the work computer without the permission from the administrator.
First, right-click My Computer and click Properties
2. Go to the "Computer Name" tab and click Change
3. Type the new name making sure it is the same as the workgroup of the other computers in the network.