Using "an audio cable from output to input on the back" to "record what u hear" is not really a good idea, because usually you get low quality recordings by this method.
First of all you need to try to
enable the "Wave Out mix" ("Stereo Mix", "Record What you hear") in Windows 7 / Vista:
- Go to the Control panel and double click the "Sound".
- Select the "Recording" tab
- Right click on the background of the tab and select "Show Disabled Devices"
- Find the "Wave Out mix" ("Stereo Mix", "Record What you hear") item, right click on it and select Enable.
Now you can capture audio from any program in Windows.