Workgroups are an easy way of grouping a collection of network PCs (for example, all of the computers in your house could be one). When you get your PC you may find that it is already of a workgroup and want to change it, or perhaps you need to join a new workgroup.
To start this process, press WINDOWS KEY + PAUSE/BREAK to load up the System information window. Then click Change Settings under the Computer Name, Description and Workgroup settings menu:
Then, click Change:
Now type in your new workgroup into the appropriate box and then click OK:
You are now a member of the new workgroup and should be visible to other networked PC's.