Hi Gerald,
- What is the make and model of the computer?
By default you will have Orange, Green and Blue colored sockets on a typical desktop computer. You may try connecting to different sockets and check which will fit into it and works.
Microphone: Orange color
Line-in: Blue
Line-out: Green
For more information, refer to the link.
http://windows.microsoft.com/en-us/windows/connect-audio-device#1TC=windows-7 (Applies to Windows 8)
Hope this information helps. If you have any concerns, please let us know.