|You need to go into your sound card configuration and set the input source to Line in and adjust the level. It is probably set for Microphone at the moment. Unless you have a good quaility sound card with a built in mixer, it is usually one or other but not both.|
For recording music, Sound Recorder is not very goods. It is really only good for recording short clips of a few seconds duration.
For music recording download and install audacity. It is free.