There is no room to enter a domain.

Hi,
I'm assuming that the operating system is XP.

Log in to your account as you usually would. Right click on My Computer and select Properties from the list. Click on the Computer Name tab. Where it says "To rename this computer or join a domain" click on change. A new window will pop up so click on Workgroup. In the typing plane if it say's MSHOME, delete that and type WORKGROUP make sure you type it in uppercase (capital letters).
When you've done that click OK.
The computer will tell you that you have to restart the computer for the changes to take effect so please restart the computer.

Once the computer has restarted you can check if the domain has changed to WORKGROUP.

Please post back if you need anymore help.

Regards.